Looks ok to me, but just a note, Thralls cannot be created out of players or boss class monsters. Otherwise you'd be constantly PK'ing and looking to last hit bosses. Also the stolen skill viea apex predetor is only 1, IE you cannot have more than one skill available via it at a time (Otherwise You could end up OP, very fast). Power wise that's about it.

Though it may need a little bit of lore-ajust and renaming, As it seems to be a bit a-jar with the current Lore. Maybe ajust it from vampire To 'Dark Mage' and then specalise it in to 'Blood Mage' and 'Litch Mage.' Simply because it seems Undead are more likely to be the foe in this sort of game. Basicly, Power wise, see above, my biggest bugbear is in the lore-iffy.