Snake, Polymorphing Captain

While Snake, Polymorphing Captain is tapped:
he gains hexproof.
{4}{g} exile Snake, Polymorphing Captain: create
a 5/4 T-Rex dinosaur token with menace. It has:
when this token leaves the battlefield: return
Snake, Polymorphing Captain to the battlefield.
{7}{r}{g} exile Snake, Polymorphing Captain: create
a 9/7 Copper Dragon token with flying. It has:
when this token leaves the battlefield: return
Snake, Polymorphing Captain to the
battlefield tapped.