Ahab, Grand Triber

Changeling (This card is every creature type)

This was fun...—When Ahab enters the battlefield or after you draw you first card on your turn choose a creature type, creatures you control gain the chosen creature type in addition to their other creature types (you cannot pick the same type twice in a row)

...while it lasted—Sacrifice 2 creatures you control, Ahab phases out

"I am the arch-enemy" - Ahab