Chameleon, Master of Disguise is a uncommon Legendary Creature — Human Shapeshifter Villain card from Through the Omenpaths (OM1), collector number 46.
You may have Chameleon enter as a copy of a creature you control, except his name is Chameleon, Master of Disguise. Mayhem {2}{U} (You may cast this card from your graveyard for {2}{U} if you discarded it this turn. Timing rules still apply.)