[konming]

Shadow blast is death magic. Blood magic in combat is not very effective. Sure there are a few spells that are good. Summon imp is good to distract enemies. Hellfire is a decent low level falling fire like spell. Blood rain has its use sometimes. Leech is a very potent spell. Life for a life can kill lots of SCs from Fomoria kings to Seraphs. Infernal prison and its icy counterparts are also good against SCs.

However the biggest problem with blood magic, aside from absurb high fatigue, is that your gems are acutally units and can be easily defiled by earthquake and like. Even if they are not killed, they can longer be used as "gems".