msem-instigator

Ophan Titan gets +3/+3 as long as there are no nonland cards in your graveyard.
Morph {1}{G} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

When Ornery Bull enters, return a creature you control to its owner's hand.

All creatures able to block Osheen Courtier do so.
Persist (When this creature dies, if it had no -1/-1 counters on it, return it to the battlefield under its owner's control with a -1/-1 counter on it.)

{G}, Tap an untapped Nymph you control: Overgrown Beast gets +2/+2 until end of turn.

Whenever Overgrowth Host attacks, germinate. Then creatures you control that are Saprolings or have counters on them gain trample until end of turn.
Saprolings you control get +1/+1.

This spell can't be countered.
Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Haste (This creature can attack and {T} as soon as it comes under your control.)

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

At the beginning of your end step, if there are three or more creature cards in your graveyard, put a +1/+1 counter on target creature you control.

Vigilance

Revive {3}{G} ({3}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

At the beginning of your upkeep, mill two cards.

Flash

At the beginning of combat on your turn, you may have Regurgitator Ooze consume. If you do, it gets +2/+2 until end of turn. (To consume, sacrifice another creature or exile a creature card from your graveyard.)
When Regurgitator Ooze dies, return a card exiled with it to its owner's hand.

Rei, the Supplanter gets +1/+1 for each Forest you control.
At the beginning of each player's end step, if that player didn't play a land this turn, create a Forest token.

Trample
When Resolution of Stone enters, put a +1/+1 counter on target creature you control.
Revive {4}{G}{G} ({4}{G}{G}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Rhudai Fieldtiller gets +1/+1 for each enchanted land you control.
At the beginning of your end step, untap each enchanted land you control.

Deploy 2 (As this enters, you may tap any number of other creatures you control with total power 2 or more.)
When Rogue Groundskeeper enters deployed, exile up to two target cards from a single graveyard.

When Rootbound Awakener enters, create a green Aura enchantment token named Vivification attached to target creature or land. The token has enchant creature or land and “Enchanted permanent is a creature with base power and toughness 5/5 in addition to its other types.”

At the beginning of combat on your turn, Ruination's Hand gains flying until end of turn if a creature you control or a creature card in your graveyard has flying. The same is true for first strike, double strike, deathtouch, hexproof, haste, indestructible, lifelink, menace, reach, trample, and vigilance.

Alpha (You may have this creature enter with a +1/+1 counter on it. If you do, it becomes alpha and can only attack alone.)
Ruthless Predator can't be blocked by more than one creature.

Poisonous 3 (Whenever this creature deals combat damage to a player, that player gets three poison counters.)
When Sankataar Assailant enters, choose a counter on target permanent or player. Give that permanent or player another counter of that kind.

Untap all creatures and lands you control during each other player's untap step.
Ascend {4}{R}{R}{R} ({4}{R}{R}{R}: Exile this creature, then return it to the battlefield transformed. Ascend only as a sorcery.)

{2}{G}: Scarred Brawler gets +2/+2 until end of turn.

Reach
When Scavenging Pack enters, you may destroy target artifact with mana value 2 or less.