Dedicated Espers are by far the most powerful character type in Caves of Qud. They're also somewhat slow to start, and require some knowledge of which mutations to learn as you advance, so they're not necessarily a good choice for a beginner; but with the right initial mutations, even the early game won't be too tough.

The main idea behind an Esper build is to raise your Ego and / or Willpower very high; these stats improve every mental mutation you learn. Then you take the Esper mutation, which ensures all your mutations will be mental, and focus on learning as many powerful mental mutations as you can as you level up. This guide will go over how to build a character based around this core concept, which mutations to focus on, and what other choices and strategies you can use to support your core mutation-focused strategy.

EDIT 7/15/2017: Espers have received a sort-of nerf; depending on your total mental mutation points, you will now be hunted by enemy Espers from other dimensions. They behave a bit like evil twins, so if you're familiar with that disadvantage you should have an idea of what to expect. One thing to keep in mind is that since they're all Espers, anti-Esper strategies are now much more important, especially Light Manipulation, to reflect their own Lase attacks; and Teleportation, to escape from their Force Wall traps and to flee the field entirely if you encounter something beyond your capabilities. You can also drain Ego from Esper Hunters you beat. The overall build still works, especially in the early game, but experienced players may want to consider going primarily for Willpower instead of Ego and rely on draining Ego from Esper Hunters instead.

EDIT 8/29/2020: More nerfs have hit several Esper powers. I've tried to update the guide to reflect this, but I may have missed a few points. The most important point is that Ego Projection now costs 4 points at chargen instead of 2, which makes the recommended build with it impossible and makes it less appealing to start with in general; switched to just Teleport Other for now. Additionally, Sunder Mind now takes much longer to kill things with and has a massively-increased cooldown. Finally, Mental Mirror has been severely nerfed overall.

Ego is your most important stat by far. Raise it to 24. In the long run, every point of ego bonus (which you get for two points of ego) adds a level to all your mental mutations. This fact is the whole reason you are playing an Esper in the first place, so raise your Ego as high as it can go. This has other benefits; Ego also lowers the prices of things in shops and improves your success with Proselytize and other Ego-based skills. One major warning for Ego is that your mutation levels are capped at half your character level, so you won't get the full benefit of your 24 Ego initially... but the steep discounts you get at shops will more than make up for this, and later on the benefits are outrageous. Also, put all the attribute gains you get from leveling up into Ego. Trust me on this, it's important.

Willpower is useful because it lowers the cooldown of all your activated abilities, including mutations, (by 5% per point over 16, with penalties instead if you leave it lower than that), but I would recommend against raising it above 18; the small bonus you get just isn't worth giving up the options you get from stat points elsewhere. Note that several important mutations (Force Wall, Teleport, Mass Mind) have their cooldowns decrease with level anyway, usually far more dramatically than you can get out of Willpower. The one advantage Willpower has over Ego is that you get its full benefit in the early game, whereas the cap on mutation levels means that you need to level a bit to get your full Ego benefits. Still, I recommend you focus on Ego. Also, note that benefits from Willpower are capped - the lowest you can reduce cooldowns is to 20%, which happens at 32 willpower; you also can't reduce anything below 5 turns of cooldown. I don't recommend you even shoot for that cap (raising Ego is more important), but definitely never raise it past 32. It does basically nothing at that point.

Toughness is vital. No matter how good you are, you will get hit eventually. Raise it to 18.

I would recommend spending the remaining points raising your Intelligence to 18 as well; there are many useful skills to spend the skill points it gives you on, and 18 intelligence means you can learn basic tinkering once you reach level 6 (you get bonuses to all your stats as you level), which is nice. But this is less essential; you could put these points in strength or agility instead (or squeak out a bit more Willpower, though I don't advise it) and it wouldn't be the end of the world.

Let's go over the basic rules to make sure you know them. You start with 12 points of mutations to spend, and can get more from drawbacks. Sadly, the mental drawbacks are mostly fairly irritating.

You also get 1 mutation point per level; 4 of these can be spent to learn a new mutation (you get to choose one of three random ones.) This is how you will be spending all your mutation points; there's no point in leveling them individually when your massive Ego is going to boost them for you. Note that these are not the same as the points you spend on mutations at chargen.

Mutations have different costs at chargen, but cost the same amount when you get them in play. Therefore, ideally, you want to buy cheap ones at chargen, and get the expensive ones as you level up... although this is trusting the RNG to an extent.

The Esper mutation, for 1 point, limits you to learning only mental mutations. This is a good thing, since it means the new mutations you get from spending those mutation points will all be mental and will all benefit from your Ego. As you probably guessed from the fact that this is an Esper guide, we're taking that.

Now, Unstable Genome, for 3 points, causes you to learn a random mutation (again, chosen from three) as you level up. Each purchase buys you one random mutation later on. Obviously, this is beneficial if you can use it to get a 5 point mutation later for only 3 points now, but you're trusting the RNG. This is something to buy once you're comfortable with the game and confident that you can survive with fewer mutations early on; generally speaking, you'd buy it instead of mutations that cost more than 3, while loading up on whatever valuable mutations cost 3 or less.

Aside from those, the most valuable mutations for a mental mutant to start with, in general, are:

Light Manipulation

This gives you a reliable source of damage. It never misses, and scales well as you go up in level (provided you keep your Ego maxed.) It costs 4 mutation points, but is generally worth it. You should put this on every esper unless you're very confident of your ability to survive the early game without it. While its damage doesn't scale up quite as drastically as most other offensive mutations, it's still valuable even later on, since it lets you kill weaker enemies without wasting a powerful mutation. It costs 4 points, but is generally worth buying at chargen. I recommend binding Laze to its own key from the ability menu, such as 'Z; this will make it easy to use it as your primary method of attack.

Force Wall

This mutation is golden. It can save your life by walling off a dangerous enemy. It can be used offensively to wall an enemy in and then finish them off with a gun. It can be used to save allies at range, to isolate enemies who have weird powers you don't want to deal with, and to generally deal with anything you can't deal with in any other way. It's incredibly versatile, since you can place the wall any way you want. Note that if you place it over someone (including yourself), they won't be pushed or trapped, but can step out onto any adjacent square; so if you have an adjacent enemy you need to escape, you can place a wall over yourself and then back out of it, and they won't be able to follow. Of course, you can wall all 8 squares around an enemy to trap them completely. Force Wall's cooldown is a flat 100, however, making it more of an emergency option.

Clairvoyance

This mutation might seem minor at first, but it's one of the best an Esper can have. If you're facing a ranged attack from outside your field of view, it lets you spot what's shooting at you and fire back. It lets you keep tabs on your allies. It lets you target several other mutations (like Sunder Mind) through walls, meaning you can kill things and they can't fight back at all. Combined with Teleportation, it lets you teleport to places you haven't been. Also, at mutation level 15, it reveals the entire map. Did I mention that? Obviously our goal is to be omnipotent, but being omniscient is a nice first step. Also, it costs 2 (count them, two) points. Don't ask questions. Grab it at chargen and walk away while whistling innocently.

There are many other valuable mutations, but I recommend learning most of them as you level. Still, most of those are also good options at chargen if you're more concerned with surviving the early game. Squeeze in whatever else you want with your remaining points, depending on which drawbacks you're willing to take. If you don't want any drawbacks, your only real useful option is Teleport Other with your remaining points, but it's not particularly essential and anything could do.

Summary

The above build, using Teleport Other: BAEEMMMUABDCDJDLDY

These are the mutations I generally recommend you learn as you level up... although starting with them certainly can't hurt. I've ordered them, roughly, in terms of importance, although it's debatable with the ones further down.

Teleportation

Chariot of the gods. Teleports you anywhere on the level that you've ever seen, including places you've only seen with Clairvoyance. With Teleportation + Clairvoyance you can simply bypass many dangers, if you want. More importantly, though, it can get you out of trouble and keep you out of sight of the big nasties trying to kill you, letting you kill them remotely with your own powers instead. This is a lifesaver. Unfortunately, it costs 5 points at chargen, so you might want to learn it later instead, although if you're new to the game starting with it can dramatically increase your survivability. If you don't start with it, learning this mutation should be by far your highest priority; grab it no matter what if it appears as an option.

Sunder Mind

What sort of mutant can't kill things with their brain? At high levels, Sunder Mind is one of the single most damaging attacks in the game; only willpower can defend against it, and most enemies suck at that. More importantly, though, it has unlimited range; you can target anything you can see (and with Clairvoyance, that means everything.) There are drawbacks, of course. First, it is slow and leaves you helpless for ten turns while you apply it. It also won't work on things with no minds (like robots and oozes.) Its cooldown of 80 is also far too long to rely on it as a primary attack method. Despite these flaws, though, Sunder Mind is still quite valuable, especially when combined with clairvoyance; the ability to attack enemies who can't fight back is incredibly useful. It's also useful when you have allies (through proselytize, temporal fugue, or beguiling) who can tank for you while you sunder the enemy, or when combined with forcefields. It does have one more significant drawback: It costs 4 points at chargen, so you might want to try and learn it later.

Force Bubble

Surrounds you with a nearly-invulnerable bubble of force that moves with you. Anything nearby will be pushed back, provided there's room. While it's up, nothing can get close enough to hit you in melee. This mutation is great, but notice that I said nearly invulnerable -- lasers and bullets will be stopped, but thrown objects won't be (the slow blade penetrates the shield and all that rot.) Also, explosions and other area-effect attacks will still hit you, as will Sunder Mind. A small number of really really damaging area-effect effect attacks (like the attacks of a Chrome Pyramid) can even destroy parts of the bubble itself; but this is rarely worth worrying about, since those attacks tend to kill you instantly anyway. The bubble's duration raises by 3 per level.

Temporal Fugue

Creates duplicates of you; the number depends on your mutation level. This power is a bit tricky. The duplicates have all your mutations, so if you have big explosive stuff, they might hit you in the crossfire. That said, this power is a very effective nuclear option. The duplicates will also take advantage of clairvoyance (including if you had it up before you used it -- they'll copy your version of it) and teleportation, meaning that if you spot a far-off enemy with Clairvoyance, and you have Teleportation, you can use Temporal Fugue and your duplicates will teleport over to murder them for you. Oh, and they get duplicates of whatever grenade you're carrying, and will throw it -- again, this risks friendly fire, but can be incredibly powerful if you need a lot of damage very quickly. Be careful, though; they tend to destroy any loot lying on the floor if you give them explosive attacks like that. 5 points at chargen again, so you probably want to wait on this. Cooldown is fairly long, too, so you can't rely on it constantly.

Pyrokinesis / Cryokinesis

Conjures a 3x3 square of elemental devastation that lasts several turns. These mutations are very effective, especially against groups, and can be targeted through walls with clairvoyance again (although the range is fairly limited.) They have a tendency to destroy stuff on the ground, though. Pyrokinesis does more damage, but lights stuff on fire (which can be bad if the fire spreads.) Cryokinesis freezes things solid; if you end up getting frozen yourself, it's actually not quite as bad, since you can still use mental mutations in that state, including teleportation. Between the two Cryokinesis is probably more useful, but both are powerful. Still, despite their power, these are somewhat lower-priority, especially since they cost 5 points at chargen. Also, note the interaction with Temporal Fugue mentioned above -- they are very powerful when used together, but also very dangerous. It's up to you if you want to take the risk, though in my experience teleportation makes it fairly safe.

Mass Mind

Resets the cooldown on all your mental mutations. Do I really have to explain why this is good? Another oddity of this mutation is that it will occasionally put all your mental mutations on cooldown for 30 turns; this is rare, and becomes more rare as it goes up in level. Since it's fairly useless unless you have lots of mutations to reset with it anyway, this is generally a mutation you want to learn later rather than one you want to start with. It costs 4 points, anyway. Note that Mass Mind is unaffected by Willpower, which makes it less attractive to willpower-heavy builds. Be warned that Mass Mind also has a chance to permanently increase your Glimmer on use, which can make it dangerous unless you're really confident about being able to deal with psychic assassins.

These mental mutations are ones that I don't feel are quite as important as the one above, or whose synergies with the basic Esper playstyle aren't as strong; still, some of them can still be quite effective, so you might have fun experimenting with them. These ones, unlike the ones above, are in no particular order.

Burgeoning

Summons a bunch of friendly plants within a range of eight squares. While it shows a 3x3 area, the plants tend to be scattered roughly around there, and you can get more than nine. There's a wide variety of plants, including both ranged and melee ones, and you get more powerful ones as the mutation's level improves. It has a range of 8, but you can target it through walls with Clairvoyance. The plants last forever, so you can build up a lot in an area if you want, too. And the mutation's cooldown drops from 105 as its level increases, all the way down to 5(!) at level 11.

This mutation is extremely powerful, but also very random; each time you use it, you get mostly the same type of (randomly-chosen) plant, and depending on what that is the results can range from devastating to completely useless. Additionally, be warned that several of the plants have dangerous AOE effects, which they'll use fairly indiscriminately - you should avoid placing Burgeoning directly adjacent to yourself if at all possible. Note that this randomness can be alleviated to an extent by using it to set up traps in advance, since you can just rest and activate it over and over until you get something useful.

One additional note: If you have harvestry, you can harvest from some of the plants you summon, granting access to a huge variety of cooking ingredients. Many of the plants it summons are rare and valuable (especially Yonderbrush, which can be harvested for teleportation-granting Yondercane), making this a very valuable mutation for any cooking build.

Beguiling

Similar to Proselytize, this turns an adjacent enemy to your side if it succeeds. There are some differences, though. The level cap here is 5 per mutation level; in practice, if your Ego is high (and yours is), this means it can convert people significantly above your level, whereas Proselytize is limited to your level. Additionally, it grants the creature +5 HP per mutation level, which can add up to a lot later on. You can only have one Beguiled ally at a time; but it and Proselytize track separately, so you can have one from each (though you may need to hurriedly lead your new allies into a new area to make them stop attacking each other after recruiting the second one.) Beguiling does have some disadvantages when compared to Proselytize, though. It's considered a hostile act, so if you try to beguile a friendly watervine farmer and fail, everyone in town will get angry at you (though only if you fail.) Additionally, its 50-turn cooldown is somewhat higher than Proselytize's 25 turns. But really, if you're taking Beguiling, you probably want both so you can keep two allies at once; you'll also want Inspiring Presence to raise your ally's HP even higher. And as with Proselytize, it combos with...

Domination

Gives you control of an adjacent target for an extended period of time (if you can beat their mental defenses.) Your own body will sit there and do nothing. Like Beguiling, this is considered a hostile act if you fail, although you can safely use it on your own allies. (So you can use Proselytize on a neutral target until it works, then use Domination to control them.)

Both you and your chosen target gain XP for anything you kill. You don't lose anything if your victim dies, so you can use this to explore in complete safety. In practice, though, using it like this is less awesome than it sounds, since most individual enemies are weaker than the player; outside of very early areas (where goats and beetle-baums make nice things to control) you'll have to risk your life to gain a new body if your old one dies. And if you want to equip them, you'll be risking that equipment...

There are other uses for this, though, especially when combined with proselytize or beguiling. When your allies level up, they gain mutation points, skill points, and ability points; Domination lets you spend these to improve them (even buying them new mutations, if they live long enough.) It also lets you equip them and apply skills they wouldn't normally use. Note that an ally that has learned Butchery or Scavenging will apply those skills automatically even if you're not possessing them. It also lets you equip them a bit more precisely and reliably than just handing them items via the "give" screen and hoping they equip the stuff you want.

Oh, and one other oddity. If you're controlling an ally and send them into another area, then release your control, they'll return to you the next turn, regardless of the distance. This can be used in somewhat clever ways with recoilers: Drop a recoiler, possess an ally and have them pick it up, then have them return to town to retrieve or store stuff for you, buy / sell things, and so on. When the domination ends, they'll come back to you. Be warned that they'll use their Ego to buy and sell, which is probably lower than yours.

Another possible exploit: You can dominate merchants and take all their stuff. Be warned that they'll go hostile if you fail, though.

Ego Projection

Increases one physical stat (of your choice) by twice your ego bonus for a short while. Since your ego bonus is very high, that's a pretty big boost; and since you can choose any of the three physical stats, this can be a pretty versatile ability. Note that to fight in melee effectively, you will need accuracy, damage, and defense; and by default this can only raise one of those things. However, there's some ways around that, and a number of valuable tricks...

With a good weapon (one with a high strength-bonus cap), boosted strength is very effective at breaking down walls - or at defeating enemies frozen by Cryokinesis, who you always hit. Boosted strength is particularly valuable if you can get accuracy bonuses from elsewhere, like the Long Blade tree's duelist stance combined with a counterweighted weapon.

Boosted Agility makes you effective with ranged weapons, and can also make you highly accurate with weapons that don't need strength, like gaslight weapons, vibroblades, or the Ceremonial Vibrokhopesh. It also grants you high DV, although usually you need DV-raising armor to take full advantage of it (which won't be so useful when your Agility isn't boosted.)

Boosted Toughness provides a very powerful emergency defense button (instantly granting you hundreds of extra HP); it also makes it easy to shake off poison, bleeding, and other physical afflictions. This is one of the few ways to get a lot of additional HP instantly on command, making it a good way to save yourself in a pinch. The extra HP will be lost when the duration runs out, but this cannot kill you (not directly, anyway) - at worst you will be left at 1 HP.

This mutation does have some disadvantages; the cooldown is very long, so (unless you have very high-level Mass Mind) you can't remain superpowered all the time. Additionally, it doesn't help you meet the prerequisites for most weapon skills (although the basic Long Blades stances don't have prerequisites, and decent Intelligence will let you grab Duelist Stance).

These mutations I have less to say about. Some of them can still be very useful, but they're not essential and often don't fit into the plan we're going for.

Siphon Vim

Drains the enemy's health by the mutation's level each turn for many turns, healing you in the process. Unfortunately, the enemy has to be adjacent to you to initiate it (though you'll continue to drain them at any distance after that), and it has a chance to fail based on their mental resistance (which can be pretty catastrophic if you were relying on it to save you from an adjacent dangerous enemy.) These drawbacks are the only reason the mutation isn't on the the list of important mutations; when it works, it's very strong, will make you very tough while it's in effect, and will usually kill anything you use it on. But as a dedicated Esper, you probably don't want to get up close and personal with enemies. Possibly this could be valuable in a hybrid build that sometimes gets into close range combat, though. Oh, and it has a cooldown of 200 turns, fair warning.

Psychometry

Flawlessly identifies an artifact, and teaches you how to build it if you have the right Tinker skills (actually, this seems to be bugged at the moment, and will teach you to build any artifact at all as long as you have Tinkering I.) Also it opens most locked doors for you (which won't really matter once you have Teleportation.) This mutation is fun, but ultimately it just isn't worth it -- with your ridiculous Ego, you'll eventually be able to buy the recipes for anything you want to build, and tinkering (while it can be nice) just ultimately isn't as valuable to you as your mutations are.

Disintegration

Massive 7x7 blast of disintegration centered on you, followed by stunning you for 3 turns. This is hugely destructive, especially to inanimate things like walls or robots. In terms of raw damage over a large area, this is the best mutation in the game. The problems are that it's centered on you (and you probably don't want to get near enemies), it leaves you vulnerable afterwards, it clears out walls (which is bad for you because you want to get Teleportation to use them for cover), and last but very much not least, it tends to destroy your loot. it's also really not a good idea to combine it with Temporal Fugue. With all that said, you could probably find lots of good ways to use this... but I'd recommend you go for something with more finesse.

Precognition

Save-scumming as a mutation. There's a lot of cool things you can do with this, like checking to see what mutations you'll learn (though you may have to play a bit to make the random seed for whatever you were doing advance), or buying and identifying artifacts and then reverting your vision if you didn't like them, or always getting the stat you want from Eaters' Nectar Injectors, or never failing to Dominate a shopkeeper... but its most basic function is to serve as an invulnerable defense against absolutely anything bad while its duration lasts. Be warned that the cooldown for this mutation is really high and doesn't decrease with its level; this is the main reason it's not listed as more important.

Space-Time Vortex

Summons a vortex that teleports anything that walks into it to a random part of Qud -- sometimes on the surface, but often deep underground. Occasionally (very, very rarely) things may wander out of it, too, including glowfish merchants. You don't get XP or loot from things that get sucked into it, of course (they're actually still alive, somewhere), but it does serve as a way to eliminate really dangerous foes. Oh, and you can step into it yourself, providing you with a viable but dangerous escape option (though it's less dangerous if you have a recoiler, and of course if you end up somewhere nasty you can just keep summoning vortexes and entering them until you're safe again.) You could also do weird things like use Domination to step into it and explore, or use Precognition to use it safely. Still, ultimately this mutation is more of an amusing trick than something you'd base a serious strategy on. One thing of note - the only way this mutation improves with level is its cooldown, but it does eventually reach a cooldown of 5, allowing you to spam vortexes extremely fast.

Stunning Force

Does somewhat low damage in a wide area, knocks everyone around, and stuns them. This is an alright substitute for Pyrokinesis / Cryokinesis, but much more prone to friendly fire in the hands of Temporal Fugue duplicates, and not as good at straight-out killing stuff. Oh, and it can be targeted through walls using Clairvoyance, even if its animation wouldn't make you think it could... using it like this is a bit less useful than other such mutations, though, since the damage is low.

Teleport Other

Makes an adjacent enemy be somewhere else. It's random, and you generally want to avoid letting the enemies get that close in the first place; but it does drop all the way down to a cooldown of 5 at level 11, making it pretty easy to just dismiss close-ranged opponents as they reach you. Also, it only costs 2 mutation points. Unfortunately, a lot of the most dangerous enemies in the game are dangerous at range, and this won't really help you with them... but given that this eventually makes you nearly immune to being engaged at close range, it's probably still worth a look if you have two points to spare at chargen.

Time Dilation

Slows time for nearby enemies based on their proximity; at close range and high level, it nearly stops them entirely. Another powerful option for close-range Espers... but, as with a lot of the other mutations I rejected above, the problem is that you don't usually want to fight at close range; and many of the most dangerous enemies are deadly at range. Still, this mutation is really good at what it does. Oh, and this is another mutation you should generally avoid combining with Temporal Fugue. The time dilation fields of your duplicates overlap and will stop time completely for anything inside them until they wear off (and they will wear off even in stopped time, thankfully)... but unfortunately, you are not immune to your duplicates' fields, so you tend to get frozen in time yourself. There's probably still some way to exploit the combo if you're extremely careful and use Teleportation, but I'm not sure it's worth it.

Confusion

Confusion makes every enemy in a large cone wander randomly (and imposes big mental penalties, although those rarely matter.) While it says confusion is not fully implemented yet, it appears to work fine. The 40 turn cooldown isn't that bad, and it's effective at what it does, making it good both as an emergency escape option and as a way of keeping enemies from fighting back while you finish them off with other attacks.

It's a strong mutation for more "mixed" builds, but I feel that it's not great for a dedicated Esper - a gun-user or melee combatant can easily kill anyone rendered helpless by it, but for an Esper, you could often have just dealt with them directly with another mutation, without needing to rely on some other option to finish them off. Force Wall is often going to be better at what it does. Also, some things are immune to it. Still, it's a solid mutation and can render a group of enemies more or less helpless; even with no agility and no skills, it usually isn't hard to finish off confused enemies using a gun.

Mental Mirror

Reflects Sunder Mind attacks when you successfully defend against them with Willpower, and gives you a (shamefully small) bonus to mental defenses. On top of this it has a cooldown. I'm going to be blunt, this mutation was nerfed into the ground and no longer serves any practical purpose. Don't take it under any circumstances.

These mutations can only be obtained at chargen, not by spending mutation points. They cost only 1 point, but they never increase in level. Since this makes your Ego pointless with them, they're generally a bad choice for a dedicated Esper.

Kindle

Starts a small (non-damaging) fire at moderate range. This mutation does have some uses. It can reduce the danger of cold damage, or increase the danger of fire damage; and while it does no damage directly, it can ignite webs or boil liquids into surprisingly devastating steam (although sadly in both cases the resulting damage awards you no XP.) It can illuminate areas at range in order to let you target distant enemies in the dark, too, although Clairvoyance kind of does that better. Unfortunately, 1-point mutations don't increase in level, so while I'd say this is the strongest 1-point mental mutation, it is still sort of a waste for an Esper.

Sense Psychic

Warns you of nearby psychics. In addition to pinpointing obvious psychics, it can alert you about otherwise innocent-looking uniques who have mental powers. Ultimately, though, psychic powers aren't that common in Qud, and you have Clairvoyance anyway. Again, doesn't gain levels.

Telepathy

Lets you talk at sight range. With Clairvoyance you can talk to anyone on the current screen. It lets you avoid the penalty for losing your tongue to glotrot, but you can cure that if you know what you're doing; and there doesn't seem to be much other use for it.

You want to be an Apostle. The +2 Ego is essential. Don't be a Graybeard; the Willpower isn't as important in the long run, and most of their skills are less useful to an Esper. The Water Merchant skills are even less relevant. Meanwhile, the Apostle skills...

Proselytize is incredibly valuable. In the early game, you should try to have a proselytized ally at all times (if you're without an ally for whatever reason, keep spamming it on a Watervine Farmer, a goat, or a beetlebaum until it works, depending on your level.) Later on (once you start teleporting everywhere) it becomes a bit less useful, but it's still nice to have. The main thing to understand is that it works on almost everything. Watervine farmers, snapjaws, giant crabs, sabertooth tigers, oozes... everything. You can only have one ally at a time with it, but they're very very useful; they can provide additional damage, block enemies from reaching you, cover your retreat if you need to escape, and generally provide support. They make Force Wall more powerful, too (because you can cage monsters in with them to force them to fight your ally instead of you.) And if your ally dies, you can always try to Proselytize an adjacent opponent to get yourself out of a pinch; with your high Ego it is reasonably reliable and can often save your life. Proselytize also has strong synergy with Dominate, if you get that mutation, since you can use Dominate to equip your ally and have them spend the attribute, skill, and mutation points they get as they level up. Note that you cannot proselytize anything above your level, so it will always fail on "tough" or above enemies.

Intimidate is also a very useful panic button early on; scaring adjacent enemies away is often as good as killing them, since you can either retreat or blast their retreating backs.

Your skill options beyond that are somewhat limited by your lack of agility or strength, but most of the available options can be valuable.

From the Persuasion tree, I strongly recommend you learn Menacing Stare -- it'll give you another way to make enemies run away, which can be valuable if you have something nasty at close range while your other stuff is on cooldown. And while its range of 5 isn't huge, it's far enough to drive away dangerous ranged attackers that are outside the range of Intimidate. Remember that a fleeing enemy won't attack, so a perfectly valid (if someone harsh) option is to use Menacing Stare or Intimidate to make an enemy flee, then Laze or shoot them in the back. It also combines well with Proselytize and minion-based strategies, since you can use it to save your allies (who don't always know when to retreat) by forcing enemies to back off from them.

Berate, meanwhile, basically makes an enemy suck -- they get steep penalties to to-hit, DV, Ego, Willpower and Quickness. The last one is particularly noticeable; Berated enemies slow down significantly.

Inspiring Presence applies a 4 * Egomod hitpoint bonus to your followers. Since your ego is going to be very high, this bonus can be significant (especially if you take Beguiling and have two followers as a result).

Don't take Snake Oiler if you're thinking long-term. The best prices you can get cap out at an Ego bonus of +9; since you'll aim to reach that eventually, Snake Oiler will eventually be useless to you, and even before then, you get diminishing returns. Snake Oiler is an excellent skill for anyone who has just a little bit of Ego (just enough to qualify for it), but it's bad for a heavily Ego-focused character like an Esper.

Tinkering is much more valuable now that you can add mods to your equipment; while you're unlikely to be able to go above basic tinkering, your high Ego makes it easy to buy disks and scrap from people like Argyve, so you'll be very good at it. Depending on what mods you get, you can get free DV or AV, reduce the weight of your equipment to compensate for your low strength, and scope or counterbalance your weapons to compensate for your low accuracy. Being able to craft grenades as needed also adds a bit of versatility to your character, although once you have enough mutations you're unlikely to need them very often. Finally, being able to deconstruct stuff you find into bits allows you to essentially carry more loot, giving you a way to benefit from all the Goatfolk with heavy guns you encounter in the wild later on.

EDIT: One other detail I forgot to add earlier that's worth mentioning here: The Apostle starting skills of Prostyltize and Intimidate can both be learned from guaranteed NPCs via the water ritual system (Prostyltize from Mechanimists like the high priest at the Six Day Stilt; Intimidate from Warden Indrix in Kyakukya.) This slightly decreases its value. That isn't something you should really worry about unless you're confident with the early game anyway, though, and none of the other options are dramatically better.

Your high ego makes prices cheap; take advantage of this. Buy up all the bullets offered by any merchant you encounter, and all the vinewafers you can get your hands on. Anything else weight-free should generally be purchased... definitely buy a bunch of bandages and salve injectors. Eventually your Ego will reach the point where you can basically trade things back and forth at virtually no loss.

But mostly, carry a gun. This is particularly important with Force Wall, since you can shoot through it with a gun (and not with light manipulation); even very powerful opponents can often be killed by boxing them in with forcefields and shooting them repeatedly. It also gives you a backup option if all your mutations are on cooldown.

Grenades work similarly, but you probably don't want to carry too many due to the weight. If you learn tinkering, you can make them as you need them, anyway.

Obviously you want equipment to raise your ego as high as possible. Beyond that, you want to raise your AC -- your DV is going to suck anyway due to your low agility. Don't rely purely on forcefields; later in the game, there are lots of enemies that can throw stuff through them. This is why you have 18 toughness, too.

One note when it comes to ego-raising equipment: You can cut off an enemy's face and wear it for an Ego boost. The hard part is that you have to cut it off while fighting them, which is only possible in two ways, both of which happen at random. One is by using the Axe skills of Dismember or Berserk; you're unlikely to be able to (or want to) learn them yourself, but if you have Domination you could consider having an ally learn them. The other option is to use a weapon with the serrated mod. Unfortunately, in both cases the chance is low. It's also possible (in theory) to get a copy of your own face by fighting something like a Madpole until they cut it off, then regenerate it with Ubernostrum tonic; however, you're quite likely to die or lose other limbs in the process, so this is really only an option if you have Precognition to try repeatedly until it works. It might be slightly safer to lead proselytized allies to Madpoles and let them get their face ripped off.

Even if you have light manipulation, carry a backup light source (and try to get a glowsphere or floating glowsphere as soon as possible.) Light manipulation has a nasty drawback where the light radius it provides decreases as you use it; if you're not careful, you can end up in the dark with no more laze shots... not a good place to be.

With 10 Strength and 10 Agility, you are only really going to be good at melee for brief windows when using Ego Projection, if you learn it. Still, Qud tends to throw enemies with a wide variety of threat-levels at you, and it's useful to be able to kill weak enemies in melee at higher levels. Vibroblades, Gaslight weapons, or the Ceremonial Vibrokhopesh can negate your lack of strength. Short Blade Expertise or Duelist Stance can partially compensate for your low accuracy; with those, perhaps some agility-boosting equipment, and a weapon that doesn't rely on strength, you can kill weaker things in melee.

A somewhat niche late-game option is to wield the Fist of the Ape God, a cudgel dropped by the ape deity found in a randomly-hidden dungeon somewhere near Kyakukya. The Fist grants +4 Ego (obviously useful to us) and +3 to-hit (making up for our abysmal agility, especially if combined with Cudgel Proficiency); it also has a decent base damage and allows unlimited strength bonus, making it brutally dangerous when combined with Ego Projection. However, there's a catch; it has a whopping weight of 120, so with your low natural strength you will realistically need a Hoversled and multiple Spheres of Negative Weight just to lug it around.

What if I told you you could learn as many mental mutations as you want, for free? Well, you can't. Not entirely for free. You can, however, learn them by spending reputation with the Seekers of the Sightless Way, bypassing the need to gain levels and mutation points; and you can theoretically grind this to learn as many as you want.

In practice, of course, Seeker faction leaders can be hard to find, and reputation with that faction is hard to get, and you'll need to get it up a lot before they'll even talk to you, and even if you find one, they'll only teach one mutation and it may be one you already have.

You've probably met lesser Seekers if you've played enough - the annoying little guys who try to sunder your mind. Unfortunately, those guys can't teach you anything; you need the purple unique faction leaders, with reputations and all, one for each mutation you want to learn, and they are rare. You can sometimes find them in the wilderness. I am not sure yet, but I believe a high Psychic Glimmer increases the chance of encountering them (one advantage to having it, despite the drawbacks.)

Before we go any further I should mention that this is a fairly advanced trick. It takes time and luck and often you just won't find a Seeker leader at all; and if you do, trying to keep them alive is dangerous - they're powerful Espers, capable of posing a threat even to another Esper like you.

But it can still be worthwhile to pursue this; even one or two potential bonus mutations are not something to turn your nose up at, and the possibility of finding new 'free' mutations in the wild is too much to completely ignore. Several things to keep in mind if you do this:

1. You will want to try and find Pages from the Annuls of Qud, either Seeker-chapter ones or, more likely, blank ones you can apply to them. This isn't easy, but they're sometimes sold by bookbinders in the Six-Day Stilt, and they now refresh their wares every so often. The ideal thing to do is to raise your reputation with them to positive levels before encountering any, but that is usually not practical.

2. You should also pay particular attention to any Seeker reputation on other uniques you find - water-ritualing ones who are popular with them, and killing (or at least not water-ritualing) any who are unpopular. Reputation with the Seekers seems a bit rare, though.

3. When you do find a Seeker faction leader, you will want to keep them alive, even if they're hostile. Proselytizing or Beguiling them will let you talk to them (and begin a water ritual, which will raise your reputation with them.) You can then get a bit more by trading them secrets and if you have the appropriate skill to increase your water ritual reputation gain. Be warned that if you Proselytize or Beguile them, they will eventually lose their old faction (this seems to happen if you leave them behind and later come back), which means they can no longer teach you their mental mutation; it doesn't happen immediately, so you can use it to get them friendly to the point where you can talk to them and then hope you can afford their mutation later, but it's a risk if you cart them around in hopes of learning from them later.

4. Mass Mind inflicts a massive Seeker faction reputation penalty. This is another reason you might want to wait on learning it, despite its power - most reputation penalties don't matter, but to an Esper, this one does.