Imp: This little creatures are the back bone of ur Dungeon they can build and dig gold. They are not the strongest of creatures but when they are level 10 they r very good.
Fly: I find these very annoying sumtimes when they fly off and get killed, also dont put them with spiders coz they will fight.
Beetles: These are good, dont get them on later levels but they are good 2 use on the earlier levels.
Warlocks: They come when you first get a libaray, they are very good on later levels when they can get Hurricane.
Bible Demon: This come when you have big enough hatchery, they like 2 work in workshop iof u have 1, but my advice is 2 put them in training.
Troll: They come when you have made a workshop, they like working in there and i would say that you should put them in there.
Orc: They come when you have a barracks, if u train them it doesn't take long for them to reach level 10 at all.
Mistress: These come when you have a Tortue chamber, they are very good at fights but b warned coz they like being in ur tortue chamber.
Horned Reaper: These get angry alot, and they need to be kept away from all the rest of the creatures. You will need to build them a different part and put a door and lock it.
Vampire: You will get these when your imps take the dead peeps to ur graveyard. Don't put them with Warlocks tho.
Skeleton: These come when there is an emeny in ur prison and they die then they become a skeleton. Don't put them with Bible Demons.
Ghost: These come when u tortuer sumone. They can angry easily and they like the temple.