Ivy Lane Denizen

Whenever another green creature you control enters, put a +1/+1 counter on target creature.

Timberwatch Elf

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

Abomination of Llanowar

Vigilance; menace (This creature can't be blocked except by two or more creatures.)
Abomination of Llanowar's power and toughness are each equal to the number of Elves you control plus the number of Elf cards in your graveyard.

Hunting Triad

Create three 1/1 green Elf Warrior creature tokens.
Reinforce 3—{3}{G} ({3}{G}, Discard this card: Put three +1/+1 counters on target creature.)

Golgari Findbroker

When Golgari Findbroker enters, return target permanent card from your graveyard to your hand.

Imperious Perfect

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

Armorcraft Judge

When Armorcraft Judge enters, draw a card for each creature you control with a +1/+1 counter on it.

Rishkar, Peema Renegade

When Rishkar, Peema Renegade enters, put a +1/+1 counter on each of up to two target creatures.
Each creature you control with a counter on it has "{T}: Add {G}."

Llanowar Elves

Shaman of the Pack

When Shaman of the Pack enters, target opponent loses life equal to the number of Elves you control.

Woodland Champion

Whenever one or more tokens you control enter, put that many +1/+1 counters on Woodland Champion.

Wildborn Preserver

Flash (You may cast this spell any time you could cast an instant.)
Reach (This creature can block creatures with flying.)
Whenever another non-Human creature you control enters, you may pay {X}. When you do, put X +1/+1 counters on this creature.

Evolution Sage

Landfall — Whenever a land you control enters, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Eyeblight Cullers

When Eyeblight Cullers dies, create three 1/1 green Elf Warrior creature tokens, then mill three cards. (Put the top three cards of your library into your graveyard.)

Deepwood Denizen

Vigilance (Attacking doesn't cause this creature to tap.)
{5}{G}, {T}: Draw a card. This ability costs {1} less to activate for each +1/+1 counter on creatures you control.