We could try dragons. They are pretty versatile power-houses which are classically depicted as evil. Necromantic creatures have been done to death, but aiming for a "binding of fallen souls into war" thing could work. Ummm... Greco-Roman monsters have a lot of options, though mostly rely upon special tricks, like regeneration or poison or bad-hair-day-itis... they are such a disparate group though that it is difficult to bring them together under a single heading. We could try contagious monstrousness, like werewolves or vampires or zombies or something... acting as a conversion to whatevr else we make and possibly some of the stuff the enemy makes. Or giants, ogres, trolls, something like that. Just D&D trolls would be a solid option. A variant with a new regeneration weakness would be easy enough and some elements can be resisted with equipment...
Hmm, while I think Dragons wouldn't be TOO hard to do with our current resources, I feel like they fall into the problem of lacking hands, not that we couldn't correct it I suppose, there's also the possibility that draconic creatures of some variety come standard with the fire plane.
Undead, while done to death(apologies for the pun), would be quite a good option for a basic frontline soldier.
As for greco-roman monsters, honestly I think we'd be better off just trying to design them individually
without research for specific roles.
Contagious monsters seem like kind of a full turn project and very likely to be shackled up with some kind of major weakness to stop them from being ungodly powerful, but I suppose they would certainly work.
And just basic Trolls I think would be a rather good idea.
Hmm, alright how about this.
Research: DragonsDragons, winged fire-breathing reptilian behemoths, they seem to be nearly a constant in worlds of magic and monsters. It was only natural that our already present leanings towards fire would drive us to look into creatures of their like. This research is, quite simply looking into the creation of dragons and dragon-like beings. Particularly focusing on their firebreath and hard-scaled reptilian bodies.
Action:
Research Dragons (1): Failbird105
Research Etching Darkness crystal ():
Research Mistress of the Unending Darkness (1): Frostgiant
Design Body of Flame ():
Design Blackscales (1): Crazyabe