Let's start with the basics and continue from there.
As you progress through the instances (tutorial), you will unlock several classes.
You can unlock all these skills by just accepting the class-quest and kill enemies.

The only thing you will have to do is to find a comfortable spot on a map where you can groups of enemies that are easy to kill. Use AoE (Area of Effect) skills to finish them off quickly.
Just find a spot where you can pretty much one-shot groups of enemies.

My personal favorite to kill groups of enemies is in Antirius's Cave in Satria.
At the Vespers. There are several big groups of about 8 to 10 enemies and some small groups of 2-3. There are also groups of 2 specials (tank, dps, supp) flying around for you to kill.

With these you'll be able to find mobs faster than usual, you won't have to do much searching in random maps. These are also really convenient for Directives and Bastion-quests.

Be sure to play the instances on a lower difficulty, this way you kill the enemies faster and easier. The easiest would be to start an instance on the lowest difficulty. It does not affect the percentage you get for your Flavius-quests.
Receive the quest, kill everything you find in the instance and restart it till you're done. Every time you finish the quest you can receive the new quest and continue killing everything. You can even finish/receive quests during combat, on lower difficulty you won't get that much damage and you won't waste any percentage on your quest.


Enter Donholk Glacier. You can find it in Glyceria.
This is probably the fastest one you can finish, you can get about one and a half quest during 1 instance. It takes about 4-6 minutes to finish, depending on how fast you are.
This is definately the most entertaining one to level up.

You coulds also try Okki Island, which can be find in Satria. It's slower, but still a really good way to farm those quests.


Enter Port Naori, can be found in Linos.
This can be done in two ways. Either do the usual: kill everything, finish the map and restart. Or, you can stay in the map ONLY if you have the extra objective 'Destroy Explosive Device'. If you find one, attack it ONLY ONCE. Walk away from it, but stay close enough for the enemies to keep spawning and walking towards you. Just keep killing them, you could even go afk with autoclicker, which then kills the mobs with basic-attacks. It's not the most effective way, personally I find it pretty slow, but it's good for when you want to do something else for a moment.

Another option is Ardos Monastry, also in Linos.
Difference in percentage for the quest is minimal, but as this map has a boss which takes quite some time (10 second cutscene at start and spawn-phase).


Actually the only map you can farm on, Alakur island, found in Satria.
Just farm it, kill everything and restart the instance after you finish it.


Taron Power Station in Bellonia.
Nothing special here either, just kill, finish and restart.
This one is really annoying and really boring. It's pretty slow too for my taste. But it's one of the limited options to farm on.

The other option is Thandi Drilling Station in Artemian Mountains.
Which is even slower than Taron Power Station.

I haven't had much time to find ways to farm these. I will update these when I can, but that won't be very often, probably.

I found this when I was doing quests on Herden Temple in Bellonia.
Just kill the Oceanids (mostly Khelps) at the beginning of the map or at spot 5 & 6 on the map above in this guide.
They often spawn a floating, purple crystal/orb that you can interact with, for every one of them you pick up, you get 1 to 6 Rare Crystallites. There are also dead bodies laying around that you can examine for Rare Crystallites.
Also, a little further on the map are Cappas, which do NOT spawn these crystals/orbs.

I did not pay attention to where I get the most credits from yet. I will pay attention to that and update this part as soon as possible.

This is obtainable from just killing enemies, but if you really want a boost, you might want to do ALL the quests on the Adventures, like the ones above in this guide.