Soul's Might

Put X +1/+1 counters on target creature, where X is that creature's power.

Forest

Bioshift

Move any number of +1/+1 counters from target creature onto another target creature with the same controller.

Tuskguard Captain

Outlast {G} ({G}, {T}: Put a +1/+1 counter on this creature. Outlast only as a sorcery.)
Each creature you control with a +1/+1 counter on it has trample.

Undercity Upheaval

Undergrowth — Distribute X +1/+1 counters among any number of target creatures you control, where X is the number of creature cards in your graveyard as you cast this spell. Creatures you control gain vigilance until end of turn.

Ivy Lane Denizen

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

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 Roaring Earth: 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.

Bramblecrush

Untamed Kavu

Kicker {3} (You may pay an additional {3} as you cast this spell.)
Vigilance, trample
If Untamed Kavu was kicked, it enters with three +1/+1 counters on it.

Elvish Visionary

When Elvish Visionary enters, draw a card.

Fertilid

Fertilid enters with two +1/+1 counters on it.
{1}{G}, Remove a +1/+1 counter from Fertilid: Target player searches their library for a basic land card, puts it onto the battlefield tapped, then shuffles.

Gnarlid Colony

Kicker {2}{G} (You may pay an additional {2}{G} as you cast this spell.)
If this creature was kicked, it enters with two +1/+1 counters on it.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Inspiring Call

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Renata, Called to the Hunt

Renata's power is equal to your devotion to green. (Each {G} in the mana costs of permanents you control counts toward your devotion to green.)
Each other creature you control enters with an additional +1/+1 counter on it.

Armorcraft Judge

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

Outmuscle

Put a +1/+1 counter on target creature you control, then it fights target creature you don't control. (Each deals damage equal to its power to the other.)
Adamant — If at least three green mana was spent to cast this spell, the creature you control gains indestructible until end of turn.

Scaled Behemoth

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Karok Wrangler

Magecraft — Whenever you cast or copy an instant or sorcery spell, put a +1/+1 counter on target creature you control.

Arbor Armament

Put a +1/+1 counter on target creature. That creature gains reach until end of turn. (It can block creatures with flying.)

Imperious Perfect

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

Crowned Ceratok

Trample
Each creature you control with a +1/+1 counter on it has trample.

Celeborn the Wise

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

Elegant Entourage

Alliance — Whenever another creature you control enters, target creature other than Elegant Entourage gets +1/+1 and gains trample until end of turn.

Greenwood Sentinel

Vigilance (Attacking doesn't cause this creature to tap.)

Lifecrafter's Gift

Put a +1/+1 counter on target creature, then put a +1/+1 counter on each creature you control with a +1/+1 counter on it.

Lys Alana Bowmaster

Reach
Whenever you cast an Elf spell, you may have Lys Alana Bowmaster deal 2 damage to target creature with flying.

Forced Adaptation

Enchant creature
At the beginning of your upkeep, put a +1/+1 counter on enchanted creature.

Wild Onslaught

Kicker {4} (You may pay an additional {4} as you cast this spell.)
Put a +1/+1 counter on each creature you control. If this spell was kicked, put two +1/+1 counters on each creature you control instead.

Generous Visitor

Whenever you cast an enchantment spell, put a +1/+1 counter on target creature.

Song of Freyalise

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III — Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.

Kujar Seedsculptor

When Kujar Seedsculptor enters, put a +1/+1 counter on target creature you control.

Snakeskin Veil

Put a +1/+1 counter on target creature you control. It gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)