Yeah, the Abyssian demon breds are one of my favorite units. Another cool trick is that since they are also priests, can fly, and Abyssia can blood sacrifice (in addition to it's dominion spreading normally), if you have the foresight to take a high dominion (which helps push your heat anyway) you can fly in 3 or 4 blood slave laden demon bred to strategic locations (with jade knives if you've managed to get some nature magic), each build a temple and start blood sacrificing and in 3 or 4 turns you've pushed your dominion so aggressively and unexpectedly that it can be a quick kill if your opponent has a low dominion. Hmmm, as I write that I'm now not sure if that's true of EA Abyssia, or if the MA demon bred are different. Anyway, that strategy works well for MA for sure.
With EA/LA Mictlan you can do something similar with their national summons. I don't remember if one of the cheaper summons has priestly powers and flying, but that bad boy (sorry don't remember the name) at blood-7 is a level 3 priest and can forge his own jade dagger, as well as pretty effectively defend the temple all by himeself while auto-generating summons every turn.