Heartbeat of Spring

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

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.

Wilderness Reclamation

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

Awakening

At the beginning of each upkeep, untap all creatures and lands.

Seedborn Muse

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