Leon, Undefeated Champion

Dynamax ( {t}: Put five +1/+1 counters on target
creature. That creature gains first strike and trample.
At the beginning of your upkeep, put a turn counter on
that creature.Then, if there are three or more turn
counters on that creature, exile the creature, then
return it to the battlefield under its owner's control.
Activate this ability only once and only any time you
could cast a sorcery.)