Koh, the Face Stealer

Whenever a creature attacks or an activated
ability of a creature is activated, you may
exile that creature unless their controller
pays {2}. Then Koh, the Face Stealer becomes
a copy of any creature exiled this way except
its name is still Koh, the Face Stealer, it's
legendary in addition to its other types, and
it gains menace and this ability.

"Oh, it was something about stealing the face of
someone you loved."