msem-instigator

Flying
If a +1/+1 counter would be put on a creature you control, you may instead put your choice of a flying counter, a vigilance counter, or a trample counter on it.

Enchant player
Whenever one or more creatures attack enchanted player, their controller may sacrifice a creature. If they do, enchanted player loses 3 life, sacrifices a nonland permanent, and discards a card.

Whenever another creature you control dies, put a +1/+1 counter on Marshy Marauder.
When Marshy Marauder dies, create a 1/1 green Insect creature token for each counter on it.

Whenever Lackeybot deals damage to a player, choose an artifact card with mana value X or less at random, where X is the amount of damage dealt. You may create a token that's a copy of that card.

Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.
{2}{W}{B}: Ishim's Meddling becomes a 4/4 Angel creature with flying and vigilance until end of turn.

You may have Imaginative Dreamer enter as a copy of any creature on the battlefield. When it does, it stops being a copy.

Whenever an artifact you control enters, look at the top card of your library. If that card's mana value is less than or equal to that artifact's mana value, you may reveal it and put that card into your hand. Otherwise, put it on the top or bottom of your library.

When Grim Botanist enters, create a 1/1 green Saproling creature token.
Whenever a nontoken creature you control dies, populate. (Create a token that's a copy of a creature token you control.)

Flying
Whenever an opponent casts a spell, copy it. You may choose new targets for the copy.

Gestalt (When this or another creature enters under your control, you may merge it with the one in play, keeping counters and attachments. They become the permanent on top plus all abilities from under it.)
Vigilance, lifelink
Whenever an opponent casts a spell, this permanent phases out until end of turn. (Treat it and anything attached to it as though they don't exist until end of turn.)

Whenever one or more counters are put on a permanent you control for the first time each turn, create that many 1/1 green Squirrel creature tokens.
{1}{G}{W}, {T}: Proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Whenever Wild Lifescale attacks, proliferate. (Choose any number of permanents and/or players with counters on them, then give each another counter of each kind already there.)

Trample
At the beginning of your upkeep, return another creature you control to its owner's hand.

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.

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

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

Motivate 2 (When this creature enters, 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.

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

Whenever a land you control enters, 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.

Enchant land
When Cradle of Civilization enters, 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.”

{1}{R}, {T}, Sacrifice a land: Create a colorless Desert land token with “{T}: Add {C}.”
{1}{R}, {T}, Sacrifice a Desert: Destroy up to two target lands.

Unleash the Dragon deals 1 damage to any target for each spell cast this turn.

Archive 5 (As this enters the battlefield, shuffle the top five cards of your main library into a new face up library. Sacrifice this after the archived library is empty.)
Eureka! (At the beginning of each end step, you get a research counter if you cast a spell this turn. Then if you have eight or more research counters, remove them and create a Masterpiece token of your choice.)
When you get your eighth research counter, exile Turin's Study, then you may cast any number of nonland cards from the archived library without paying their mana costs.

Haste
Whenever you sacrifice another permanent, put a +1/+1 counter on Shrine Razer.

Flying, haste
Whenever Shimmering Dragon attacks, for each creature you control, create a tapped and attacking token that's a copy of that creature. Exile the tokens at the beginning of the end step.