Rot Shambler

Whenever another creature you control dies, put a +1/+1 counter on this creature.

Insect

Elemental

Tukatongue Thallid

When this creature dies, create a 1/1 green Saproling creature token.

Beast

Seed Guardian

Reach
When this creature dies, create an X/X green Elemental creature token, where X is the number of creature cards in your graveyard.

Bloodbriar

Whenever you sacrifice another permanent, put a +1/+1 counter on this creature.

Cankerbloom

{1}, Sacrifice this creature: Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

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.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Undergrowth Scavenger

This creature enters with a number of +1/+1 counters on it equal to the number of creature cards in all graveyards.

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.)

Copper Longlegs

Reach
{1}{G}, Sacrifice this creature: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)

Swarm Shambler

This creature enters with a +1/+1 counter on it.
Whenever a creature you control with a +1/+1 counter on it becomes the target of a spell an opponent controls, create a 1/1 green Insect creature token.
{1}, {T}: Put a +1/+1 counter on this creature.

Primal Rage

Creatures you control have trample. (A creature with trample can deal excess combat damage to the player or planeswalker it's attacking.)

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.

Saproling

Death's Presence

Whenever a creature you control dies, put X +1/+1 counters on target creature you control, where X is the power of the creature that died.

Fungal Plots

{1}{G}, Exile a creature card from your graveyard: Create a 1/1 green Saproling creature token.
Sacrifice two Saprolings: You gain 2 life and draw a card.

Fangs of Kalonia

Put a +1/+1 counter on target creature you control, then double the number of +1/+1 counters on each creature that had a +1/+1 counter put on it this way.
Overload {4}{G}{G} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Mycoloth

Devour 2 (As this creature enters, you may sacrifice any number of creatures. It enters with twice that many +1/+1 counters on it.)
At the beginning of your upkeep, create a 1/1 green Saproling creature token for each +1/+1 counter on this creature.

Forest

Eldritch Evolution

As an additional cost to cast this spell, sacrifice a creature.
Search your library for a creature card with mana value X or less, where X is 2 plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle. Exile Eldritch Evolution.