Wren's Run Hydra

Reach
Wren's Run Hydra enters with X +1/+1 counters on it.
Reinforce X—{X}{G}{G} ({X}{G}{G}, Discard this card: Put X +1/+1 counters on target 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.)

Lead by Example

Support 2. (Put a +1/+1 counter on each of up to two target creatures.)

Arbor Armament

Put a +1/+1 counter on target creature. That creature gains reach until end of turn.

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.)

Timberland Guide

When Timberland Guide enters, put a +1/+1 counter on target creature.

Ivy Lane Denizen

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

Territorial Scythecat

Trample
Landfall — Whenever a land you control enters, put a +1/+1 counter on Territorial Scythecat.

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.

Gnoll Hunter

Pack tactics — Whenever Gnoll Hunter attacks, if you attacked with creatures with total power 6 or greater this combat, put a +1/+1 counter on Gnoll Hunter.

Dauntless Survivor

When Dauntless Survivor enters, put a +1/+1 counter on target creature.

Soul's Might

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

Bulette

At the beginning of your end step, if a creature died this turn, put a +1/+1 counter on Bulette.