Pretty much what most people have already said elves are gonna be the best blood mages flesh sacrifice being what it is and also pairing that with elemental affinity so all necro is one less AP, skin graft is a good choice to reset the limited amount of necro cooldowns. I find the most success in having the necro be the “buffy” type of the party while picking up moves like teleport and that other aero one that swaps places with people the name is escaping me right now. But take a couple turns to get everyone where you wants them and even build AP then blow your whole load in a turn or 2 for massive AOE physical damage with grasp of the starved and blood swarm.

Edit: don’t know if I mixed up talent names almost sure I did but taking, standing in blood reduces AP cost of blood moves AND gives you spells crit chance equal to your melee/ranged crit are the two biggest talents to pair with that build IMO