Heaven's Gate

One or more target creatures become white until end of turn.

Celestial Dawn

Lands you control are Plains.
Nonland permanents you control are white. The same is true for spells you control and nonland cards you own that aren't on the battlefield.
You may spend white mana as though it were mana of any color. You may spend other mana only as though it were colorless mana.

Rith, the Awakener

Flying
Whenever Rith deals combat damage to a player, you may pay {2}{G}. If you do, choose a color, then create a 1/1 green Saproling creature token for each permanent of that color.

Dwarven Song

One or more target creatures become red until end of turn.

Spawnwrithe

Trample
Whenever this creature deals combat damage to a player, create a token that's a copy of this creature.

Hour of Reckoning

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.)
Destroy all nontoken creatures.

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Sylvan Paradise

One or more target creatures become green until end of turn.

Artifact Mutation

Destroy target artifact. It can't be regenerated. Create X 1/1 green Saproling creature tokens, where X is that artifact's mana value.

Dragonlair Spider

Reach
Whenever an opponent casts a spell, create a 1/1 green Insect creature token.