Marwyn, the Nurturer

Whenever another Elf you control enters, put a +1/+1 counter on Marwyn.
{T}: Add an amount of {G} equal to Marwyn's power.

Glorfindel, Dauntless Rescuer

Whenever you scry, choose one and Glorfindel gets +1/+1 until end of turn.
• Glorfindel must be blocked this turn if able.
• Glorfindel can't be blocked by more than one creature each combat this turn.

Haldir, Lórien Lieutenant

Haldir enters with X +1/+1 counters on it.
Vigilance
{5}{G}: Until end of turn, other Elves you control gain vigilance and get +1/+1 for each +1/+1 counter on Haldir.

Kami of Whispered Hopes

If one or more +1/+1 counters would be put on a permanent you control, that many plus one +1/+1 counters are put on that permanent instead.
{T}: Add X mana of any one color, where X is this creature's power.

Roaring Earth

Landfall — Whenever a land you control enters, put a +1/+1 counter on target creature or Vehicle you control.
Channel — {X}{G}{G}, Discard this card: Put X +1/+1 counters on target land you control. It becomes a 0/0 green Spirit creature with haste. It's still a land.

Rishkar, Peema Renegade

When Rishkar 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}."

Hardened Scales

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

Galadriel, Gift-Giver

Whenever Galadriel enters or attacks, choose one —
• Put a +1/+1 counter on another target creature.
• Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
• Create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")

Branching Evolution

If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.

Numa, Joraga Chieftain

At the beginning of combat on your turn, you may pay {X}{X}. When you do, distribute X +1/+1 counters among any number of target Elves.
Partner (You can have two commanders if both have partner.)

Kurbis, Harvest Celebrant

Kurbis enters with a number of +1/+1 counters on it equal to the amount of mana spent to cast it.
Remove a +1/+1 counter from Kurbis: Prevent all damage that would be dealt this turn to another target creature with a +1/+1 counter on it.

The Earth Crystal

Green spells you cast cost {1} less to cast.
If one or more +1/+1 counters would be put on a creature you control, twice that many +1/+1 counters are put on that creature instead.
{4}{G}{G}, {T}: Distribute two +1/+1 counters among one or two target creatures you control.

Legolas, Master Archer

Reach
Whenever you cast a spell that targets Legolas, put a +1/+1 counter on Legolas.
Whenever you cast a spell that targets a creature you don't control, Legolas deals damage equal to its power to up to one target creature.

Gwenna, Eyes of Gaea

{T}: Add two mana in any combination of colors. Spend this mana only to cast creature spells or activate abilities of creature sources.
Whenever you cast a creature spell with power 5 or greater, put a +1/+1 counter on Gwenna and untap it.

Retreat to Kazandu

Landfall — Whenever a land you control enters, choose one —
• Put a +1/+1 counter on target creature.
• You gain 2 life.

Arwen, Weaver of Hope

Each other creature you control enters with a number of additional +1/+1 counters on it equal to Arwen's toughness.

Sutina, Speaker of the Tajuru

When Sutina enters, search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Whenever Sutina attacks, you may return a land you control to its owner's hand. When you do, put a +1/+1 counter on target creature.

Yorvo, Lord of Garenbrig

Yorvo enters with four +1/+1 counters on it.
Whenever another green creature you control enters, put a +1/+1 counter on Yorvo. Then if that creature's power is greater than Yorvo's power, put another +1/+1 counter on Yorvo.

Woodland Champion

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

Legolas Greenleaf

Reach
Legolas can't be blocked by creatures with power 2 or less.
Whenever another legendary creature you control enters, put a +1/+1 counter on Legolas.
Whenever Legolas deals combat damage to a player, draw a card.

Cloakwood Swarmkeeper

Gathered Swarm — Whenever one or more tokens you control enter, put a +1/+1 counter on this creature.

Maester Seymour

At the beginning of combat on your turn, put a number of +1/+1 counters equal to Maester Seymour's power on another target creature you control.
{3}{G}{G}: Monstrosity X, where X is the number of counters among creatures you control. (If this creature isn't monstrous, put X +1/+1 counters on it and it becomes monstrous.)

Celeborn the Wise

Whenever you attack with one or more Elves, scry 1.
Whenever you scry, Celeborn gets +1/+1 until end of turn for each card looked at while scrying this way.

Dionus, Elvish Archdruid

Elves you control have "Whenever this creature becomes tapped during your turn, untap it and put a +1/+1 counter on it. This ability triggers only once each turn."