Morophon, the Boundless (Display Commander) - Thick Stock (Double Rainbow Foil) (1944) [Secret Lair Drop]

Changeling (This card is every creature type.) As Morophon enters, choose a creature type. Spells of the chosen type you cast cost {W}{U}{B}{R}{G} less to cast. This effect reduces only the amount of colored mana you pay. Other creatures you control of the chosen type get +1/+1.