Abadom
I think the next class might be overlord, from the game overlord 2 (not the anime). The class would give access to magical abilities and the ability to summon "minions". If you are not familiar with the game, the "minions" are small imps that serve the overlord and are divided into brown (physical combatants, able to ride wolves), red (fire mages, able to ride salamanders), blue (healers/necromancers sub aquatic) and green (venom-using killers capable of setting up scratches). I admit they would be a little weak to the main universe, but as you said monstrous species can evolve, it would be interesting if they could too.