Krista the Undying

: On your upkeep, if Krista the Undying lost counters since the end of your last turn, put that many counters on Krista the Undying.
+2: You may sacrifice a blood token. If you do, gain 5 life and put a +1/+1 counter on target creature. Otherwise, you gain 2 life.
-13: Target opponent loses 13 life, you gain 13 life, and destroy all artifacts and enchantments you don't control.