Aspect of Hydra

Target creature gets +X/+X until end of turn, where X is your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)

Utopia Sprawl

Enchant Forest
As Utopia Sprawl enters, choose a color.
Whenever enchanted Forest is tapped for mana, its controller adds an additional one mana of the chosen color.

Forest

Wild Growth

Enchant land
Whenever enchanted land is tapped for mana, its controller adds an additional {G}.

Silverback Shaman

Trample
When Silverback Shaman dies, draw a card.

Rogue Elephant

When Rogue Elephant enters, sacrifice it unless you sacrifice a Forest.

Llanowar Elves

Murasa Behemoth

Trample
Murasa Behemoth gets +3/+3 as long as there is a land card in your graveyard.

Scythe Tiger

Shroud (This creature can't be the target of spells or abilities.)
When Scythe Tiger enters, sacrifice it unless you sacrifice a land.

Arbor Elf

Garruk's Companion

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)