Rofellos, Llanowar Emissary

{T}: Add {G} for each Forest you control.

Chorus of Might

Until end of turn, target creature gets +1/+1 for each creature you control and gains trample.

Colossification

Enchant creature
When Colossification enters, tap enchanted creature.
Enchanted creature gets +20/+20.

Llanowar Druid

{T}, Sacrifice Llanowar Druid: Untap all Forests.

Forest

Genesis Wave

Reveal the top X cards of your library. You may put any number of permanent cards with mana value X or less from among them onto the battlefield. Then put all cards revealed this way that weren't put onto the battlefield into your graveyard.

Rofellos's Gift

Reveal any number of green cards in your hand. Return an enchantment card from your graveyard to your hand for each card revealed this way.

Overwhelming Stampede

Until end of turn, creatures you control gain trample and get +X/+X, where X is the greatest power among creatures you control.

Titanic Growth

Target creature gets +4/+4 until end of turn.

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Harmonize

Confidence from Strength

Target creature gets +4/+4 and gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it's attacking.)