Groot

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.)

{2}, {t}: Create two 0/4 plant creature tokens named Growth Wall with defender and "When this creature dies, you may gain 3 life."

Whenever you create a creature token, put an ultimate counter on Groot. If Groot has five or more ultimate counters on him, remove him from the battlefield and return him transformed.