Steal spirit sacrifices a champion's life and has your sov eat their soul to steal one of their spellcasting ranks. Awesome spell, deliciously abusable (but not practical outside of sandbox style play)
But for some odd reason its a LIFE spell rather then a DEATH spell. Meaning only "good" sov's can use it. Every other "sacrifice" type spell is a death spell and so should this one be.
Speaking of, I am going to try a sov with only book of life and see if I can min max it even further . Well, right after trying a sov with no books at all (should that even be allowed?)