msem-instigator

{T}, Pay 1 life: Add {G}.
{8}{G}, Exile Singers' Grove from your hand: Creatures you control get +7/+7 until end of turn.

Sire of the Shapeless costs {3} less to cast as long as you control three or more creatures.
Trample, haste
{G}, Reveal Sire of the Shapeless from your hand: Create a 1/1 colorless Human creature token. Shuffle Sire of the Shapeless into your library. Activate only as a sorcery.

When Sire of the Wild enters, reveal the top four cards of your library. You may put a creature card from among them onto the battlefield. Shuffle the rest into your library.

Skavi Behemoth can't be the target of nongreen spells or abilities from nongreen sources.

Resolute — Skerry Serpent must be blocked if able as long as its power is greater than its base power.

Reach

Reach (This creature can block creatures with flying.)
Whenever a creature you control enters for the first time each turn, untap Skittering Swarm. It gets +1/+1 until end of turn.

Whenever Skitterthorns blocks or becomes blocked, creatures you control gain deathtouch until end of turn.

Create a 1/1 green Squirrel creature token.
The next creature spell you cast this turn can be cast as though it had flash. As you cast that spell, it gains voracious 2. (As it enters, you may sacrifice up to two artifacts and/or creatures. That creature enters with that many +1/+1 counters on it.)

Trample

Whenever you tap a creature for mana, put a +1/+1 counter on that creature.
{T}: Add {G}.

Haste
Whenever a creature attacks, Slashing Pangolin gets +1/+1 until end of turn.

Enchant land
Whenever enchanted land is tapped for mana, its controller adds {G}.
{G}, Sacrifice Sleeping Dryads: Draw a card.

Menagerie — {1}{G}: Slipsand Hornshell gains indestructible until end of turn. Tap it. Activate only if there are five or more creature types among creatures you control.

Choose target creature you don't control. When that creature dies this turn, draw a card. Target creature you control fights that creature.

Target creature gets +3/+3 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Target creature gains deathtouch and poisonous 1 until end of turn. (Whenever that creature deals combat damage to a player, that player gets a poison counter.)
Inscribe {1}{G} ({1}{G}: Exile this card from your hand inscribed on a creature you control. Whenever that creature attacks, its controller may cast a copy of the inscribed card without paying its mana cost. Inscribe only as a sorcery.)

Creatures with power less than Sneaking Peak's power can't block it.
At the beginning of your end step, if Sneaking Peak didn't attack this turn, put a +1/+1 counter on it.

Destroy target creature with flying. (Then exile this card. You may cast the creature later from exile.)

Snowy Misthorn can block creatures with distorted as though it was tapped.

Reveal the top five cards of your library. You may put a permanent card revealed this way into your hand and the rest into your graveyard.

If you control seven or more creatures, you may cast Sociable Giant without paying its mana cost.
Trample

Whenever Solemn Stag perseveres, put two +1/+1 counters on it. (A creature perseveres when it survives damage.)

(As an Encounter enters, choose an opponent to protect it. You and others can attack it. When defense counters are removed, create a 0/0 Army token if you don't control one, then put that many +1/+1 counters on a Army you control.)
When Soli Rising enters, reveal cards from the top of your library until you reveal a creature card. Put that card into your hand and the rest on the bottom of your library in a random order.

Whenever Solvent Tide attacks, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)