Higher Magic

[Zechnophobe]

Sacrifice deals X damage to one unit, and ressurrects Y damage to another, where Y is 30%/40%/50% of X based on the level you cast the spell at. Note that higher level versions of sacrifice also do more damage, in addition to converting a better percentage.

You cannot cast it on a summon, and if you cast it on a mind controlled unit, it can only sacrifice for the unit that controlled it. IE, demonessess enthrall someone, you can sacrifice the thrall to give the Demoness more health.