[Master Shake]

Summon imp is a great cheap, early battlefield blood magic spell. Blood skill 2 to cast, blood magic research 1 or 2 (can't remember). A great way to tie up a cavalry charge or get archers to fire into their own troops (trying to kill the imps). You get fewer summons than you do with swarm, but imps have moderate attack, strength and defense and can actually inflict damage.