His first unit of Black Daimons was quite devastating. I remember them routing a whole bunch of units. However, Black Daimons have been defeated two times I think, which greatly weakened them. I assume that they work as regular units, which means cohesion and other stuff pumps them up. In any case, they have been less dangerous than we thought in Riombara's last victory in Melegra (or this could very well be associated with the fact we had over a 1000 tightly arrayed infantry and was quite difficult for them to break that).