Keeper of Balance

Hexproof
Whenever a -1/-1 counter is put on a creature, put a +1/+1 counter on Keeper of Balance and target creature you control. If Keeper of Balance has five or more +1/+1 counters on it, it has flying and lifelink.
Blood leaves a body and weakens it. The same blood enters the body an strengthens it. there is a balance to keep. Not a drop can be wasted.
-Rites of Blood, verse 13:86.