Exponential Growth

Until end of turn, double target creature's power X times.

Biomass Mutation

Creatures you control have base power and toughness X/X until end of turn.

Gelatinous Genesis

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.

Wurmcalling

Buyback {2}{G} (You may pay an additional {2}{G} as you cast this spell. If you do, put this card into your hand as it resolves.)
Create an X/X green Wurm creature token.

Mana Reflection

If you tap a permanent for mana, it produces twice as much of that mana instead.

Aether Mutation

Return target creature to its owner's hand. Create X 1/1 green Saproling creature tokens, where X is that creature's mana value.