Vampiric Clerk 4B
Creature - Vampire Warlock (Uncommon)
Whenever you gain life during your turn, put a +1/+1 counter on Vampiric Clerk.
Whenever you lose life during your turn, put a +1/+1 counter on Vampiric Clerk.
So long as your life total moves during your turn, it's power and toughness move up. Not too sure if it'll stick since it's a 5-mana 2/2 to begin with.