Darian, Master of the Skies

Flying; contract (This creature has all colors spent to
cast it in addition to its other colors.)
As long as Darian is your commander, you may
have cards of any color and lands that produce
any color of mana in your deck.
The first spell with converted mana cost equal to
the number of creatures you control that you cast
each turn with the same color identity as Darian
gains cascade.