I was surprised to see that no one has found a way to use deathcards in other gamemodes besides coop or messing with files. It's surprisingly easy just go into the console and type collectible_add collectible_(collectible type). For example collectible_Thunder, collectible_paintball, collectible_painkiller. This works without needing to use devmap, you can just load into campaign or zombies and type it in console it even works on mods. Some deathcards don't seem to work in zombies. Let me know if it works or not for you.