Eternal Wolf

When Eternal Wolf dies, you gain 1 life.
Undying (When this creature dies, if it had no
+1/+1 counters on it, return it to the battlefield under its owner's control with a +1/+1 counter on it.)
Evoke {g}{g} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters the battlefield.)