Doubling Cube

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

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.

Garenbrig Growth

Return target creature or land card from your graveyard to your hand. (Then exile this card. You may cast the enchantment later from exile.)

Virtue of Strength

If you tap a basic land for mana, it produces three times as much of that mana instead.

Virtue of Strength // Garenbrig Growth

Seedborn Muse

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

Dictate of Kruphix

Flash
At the beginning of each player's draw step, that player draws an additional card.

Dictate of Karametra

Flash
Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Wilderness Reclamation

At the beginning of your end step, untap all lands you control.

Blue Sun's Zenith

Target player draws X cards. Shuffle Blue Sun's Zenith into its owner's library.

Kruphix's Insight

Reveal the top six cards of your library. Put up to three enchantment cards from among them into your hand and the rest of the revealed cards into your graveyard.

Hydra's Growth

Enchant creature
When Hydra's Growth enters, put a +1/+1 counter on enchanted creature.
At the beginning of your upkeep, double the number of +1/+1 counters on enchanted creature.