They definetly are a strong army, especially since they are the only undead race that has access to standart 3/3/4+ knights and tougher infantry (grave guards). In a addition you have an extra caster and the combination of the movement spell + flyers can be devastating.
Another bonus is that you have acces to a second terror causing mount, which can even break even the hardest units.
The bloodlines thing looks nice but I think the Lhamia power is way to powerful, as there is nothing like that available to other races. (At least it looks for me like that on paper, 4+ chance maybe?) I know that would cause alot of cursing if I were on the receiving end of that.
