Timberwatch Elf

{T}: Target creature gets +X/+X until end of turn, where X is the number of Elves on the battlefield.

Elven Ambush

Create a 1/1 green Elf Warrior creature token for each Elf you control.

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Yavimaya, Cradle of Growth

Each land is a Forest in addition to its other land types.

Forest

Gaea's Cradle

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

Parallel Lives

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead.

Castle Garenbrig

This land enters tapped unless you control a Forest.
{T}: Add {G}.
{2}{G}{G}, {T}: Add six {G}. Spend this mana only to cast creature spells or activate abilities of creatures.

Elvish Mystic

Second Harvest

For each token you control, create a token that's a copy of that permanent.

Imperious Perfect

Other Elves you control get +1/+1.
{G}, {T}: Create a 1/1 green Elf Warrior creature token.

Elvish Champion

Other Elf creatures get +1/+1 and have forestwalk. (They can't be blocked as long as defending player controls a Forest.)

Dwynen's Elite

When this creature enters, if you control another Elf, create a 1/1 green Elf Warrior creature token.

Dwynen, Gilt-Leaf Daen

Reach (This creature can block creatures with flying.)
Other Elf creatures you control get +1/+1.
Whenever Dwynen attacks, you gain 1 life for each attacking Elf you control.