How to use blood magic effectively in battles?

[K]

Reinvigoration is the best combat blood spell. Rush of Strength is nice as well. The spells that send dudes to hell are the premier SC killers.

Otherwise, pray your mages don't cast any of the other spells (though Hellbind Heart is almost as good as Charm or Enslave and will do wonders in Assasinations).

Otherwise, blood slaves make good meatshields.