msem-instigator

Creatures you control get +X/+X and gain trample until end of turn.

Enchant land
When Cradle of Civilization enters the battlefield, search your library for a basic land card, reveal it, put it into your hand, then shuffle.
Enchanted land has “{T}: Add one mana of any color.”

Prevent all combat damage that would be dealt to you this turn. Populate. (Create a token that's a copy of a creature token you control.)

Whenever a land enters the battlefield under your control, choose one. If it doesn't share a name with another land you control, instead choose both—
• Create a 1/1 Scout creature token that's all colors.
• Put a +1/+1 counter on a creature you control.

Landfall — Whenever a land enters the battlefield under your control, create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)

You gain 3 life. Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Destroy target creature with flying.

Target creature you control fights another target creature. If either of those creatures would die this turn, exile it instead.

When Fungal Whomper enters the battlefield, you gain 4 life.
When Fungal Whomper leaves the battlefield, germinate four times. (To germinate, put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)

Motivate 2 (When this creature enters the battlefield, you may motivate target creature with less power than this by putting two +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.

Enchant land
When Grace of Timber enters the battlefield, put a +1/+1 counter on target creature you control.
Enchanted land has “{T}: Add two mana of different colors.”

Target creature gets +2/+2 until end of turn.
Landfall — If you had a land enter the battlefield under your control this turn, that creature gets +4/+4 until end of turn instead.

When Harbinger of Growth enters the battlefield, create a 1/1 green Saproling creature token.
{1}{G}, Sacrifice Harbinger of Growth: Populate. (Create a token that's a copy of a creature token you control.)

When Host of Nature enters the battlefield, create two 2/2 red and green Elk creature tokens.

Spirited (When this creature enters the battlefield, you may activate one of its activated abilities without paying its cost.)
{3}{G}, Sacrifice Jade Vault Reclaimer: Destroy target artifact or enchantment.

Choose two. You may choose the same mode twice —
• Create a 1/1 green Insect creature token.
• Put a +1/+1 counter on target creature you control.

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
When Kantra of Old Majik enters the battlefield, you may return target card from your graveyard to your hand.

Up to two target creature cards in your graveyard gain revive until end of turn. The revive costs are each equal to that card's mana cost. (Pay that creature's mana cost, Exile that card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Landfall — Whenever a land enters the battlefield under your control, add {G}.
{3}{G}: Target creature you control gets +2/+2 until end of turn.

{G}, Exile a creature card from your graveyard: Put two +1/+1 counters on target creature.

{T}: Add {G}. If you control an attacking creature, add one mana of any color instead.

Experience (Whenever this creature attacks, if it has fewer than three +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever Primal Ruffian attacks, if it has a +1/+1 counter on it, other creatures you control get +1/+1 until end of turn. (If it had no counters on it when it attacked, this ability does not trigger.)

When Rethia Cultivator enters the battlefield, you may search your library for a land card, reveal it, put it into your hand, then shuffle.

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

Whenever a land enters the battlefield under your control, you may pay {1}. If you do, create a 1/1 green Saproling creature token.

{G}{G}, {T}: Create a token that's a copy of target creature you control that entered the battlefield this turn, except it's an artifact in addition to its other types.