Grantsie, Harmless Gibbon

Whenever this creature enters the battlefield or transforms into Grantsie, put two gibbon
counters on it for each opponent.
Whenever you attack a player with at least one creature, remove a gibbon counter from Grantsie,
then, if there are no gibbon counters on Grantsie, transform him at end of combat.
You may pay {u}{u}{u} rather than pay this spell's
mana cost.