Blood magic and mana regen.

Does mana regeneration work for blood magic?
As in you regenerate health instead of mana because your health is your mana?

No it doesn't work that way, mana regeneration simply gets useless.

Blood Magic takes away all your mana, it does not convert mana or mechanics that used to work for mana and apply them to life. After you take BM anything to do with mana becomes completely useless. The upside is you can then focus entirely on life.

EDIT: it does however convert any COST mechanics to apply to life. So not only will skills cost life, but auras will reserve life instead of mana.

The only "mana" thing I am aware that works is the skill gem reduced mana or I would assume that any nodes that reduce mana for skills. They apply the reduction to your skill, before it goes looking for mana or health to use to cast it.