[TheMenacer]

How's about a crystalline life form that floats about space and converts any material that it hits into more of itself. It'd be fun to see your troops blasting away at this very slowly advancing carpet of crystals until all of a sudden "Blam" it just smacks into them and suddenly it's going nuts and running rampant throughout their ranks. Obviously there's no way to actually have something replicate itself via the Dominions 3 engine, but I'm thinking really really slow high HP creatures with a ton of mr resist or die attacks so that it can lash out simultaneously at anything in melee range.