Kruphix, God of Horizons

Indestructible
As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.

Doubling Cube

{3}, {T}: Double the amount of each type of unspent mana you have.

Mana Drain

Counter target spell. At the beginning of your next main phase, add an amount of {C} equal to that spell's mana value.

Rewind

Counter target spell. Untap up to four lands.

Seedborn Muse

Untap all permanents you control during each other player's untap step.