Ditto

Emerge {6} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's converted mana cost.)
Changeling (This card is every creature type.)
Creatures you cast have "Champion a Ditto", they cost {2} less of any color. (When this enters the battlefield, sacrifice it unless you exile a creature named Ditto you control. When this leaves the battlefield, Ditto returns to the battlefield.)