The 14th & 15th Doctors

Changeling (This card is every creature type.)
As The 14th & 15th Doctors enters the battlefield, 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.