Oran-Rief Ooze

When this creature enters, put a +1/+1 counter on target creature you control.
Whenever this creature attacks, put a +1/+1 counter on each attacking creature with a +1/+1 counter on it.

Stony Strength

Put a +1/+1 counter on target creature you control. Untap that creature.

Thriving Grove

This land enters tapped. As it enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Greenwood Sentinel

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

Jiang Yanggu, Wildcrafter

Each creature you control with a +1/+1 counter on it has "{T}: Add one mana of any color."
−1: Put a +1/+1 counter on target creature.

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.

Forest

Aggressive Instinct

Target creature you control deals damage equal to its power to target creature you don't control.

Mowu, Loyal Companion

Vigilance, trample
If one or more +1/+1 counters would be put on Mowu, that many plus one +1/+1 counters are put on it instead.

Invigorating Surge

Put a +1/+1 counter on target creature you control, then double the number of +1/+1 counters on that creature.

Jungle Delver

{3}{G}: Put a +1/+1 counter on this creature.

Saproling

Saurian Symbiote

Reach (This creature can block creatures with flying.)
When this creature enters, choose one —
• Put a +1/+1 counter on this creature.
• Create a 1/1 green Saproling creature token.

Spined Tyrranax

At the beginning of combat on your turn, you may pay {2}{G}. When you do, put a +1/+1 counter on target creature. That creature gains trample until end of turn. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Duskshell Crawler

When this creature enters, put a +1/+1 counter on target creature.
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.)