Zellok, Envoy of Entropy

Changeling (This card is every creature type.)
As Zellok, Envoy of Entropy enters the battlefield, choose a creature type.
Spells you cast of the chosen type 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.