msem-instigator

Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Igneous Pulverizer desecrates a permanent, destroy target nonland permanent.

If a creature entering the battlefield under your control causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.
{1}{U}, {T}: Exile another target creature. Return it to the battlefield under its owner's control at the beginning of the next end step.

Descended Gorge enters tapped.
{T}: Add {R} or {G}.
Morph {2} (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 Gyreon Pickpocket enters, target opponent discards a card. If a land card was discarded this way, draw a card.

Hexproof
When Uncharted Leviathan enters, target creature can't be blocked this turn.

When Eternity's Eye enters, look at the top seven cards of your library. Put up to three of them into your graveyard and the rest on the bottom of your library in a random order.
{T}: Add one mana of any color.
{2}: Put target card from a graveyard on the bottom of its owner's library.

Tracking Party enters with a +1/+1 counter on it.
{T}, Remove a +1/+1 counter from Tracking Party and exert it: Destroy target artifact or enchantment. (An exerted creature won't untap during your next untap step.)

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

Menace
Foresight — Whenever you draw your second card each turn, search your library for a card, put it into your hand, then shuffle.

Whenever you cast a spell during another player's turn, monstrosity 1. (If this creature isn't monstrous, put a +1/+1 counter on it and it becomes monstrous.)

At the beginning of your upkeep, create two 1/1 colorless Construct artifact creature tokens, then you gain life equal to the number of artifacts and enchantments you control.

First strike, vigilance
When Subnautical Legionnaire enters, choose artifact, enchantment, or Merfolk. Exile target nonland permanent you don't control until you control no permanents of the chosen type.

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
You may cast the first spell that's an enchantment, instant, or sorcery with mana value 1 you cast each turn without paying its mana cost.

When Garrison Warden enters, put a +1/+1 counter on target creature you control.
Surpass {5}{W} ({5}{W}: Transform this. This costs {1} less to activate for each counter on it. Activate only as a sorcery.)

Vigilance
Tribute 3 (As this creature enters, an opponent of your choice may put three +1/+1 counters on it.)
When Dignified Serpent enters, if tribute wasn't paid, put a +1/+1 counter on each other creature you control.

{2}{G}: Target face-down creature you control becomes a Beast with base power and toughness 5/5 until end of turn.

Until end of turn, target creature gains double strike and damage dealt by it can't be prevented.
Fuse (You may cast one or both halves of this card from your hand.)

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn.

As Destroyed Isle enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {W}, {U}, or {B}.

When Harried Submersible enters, target opponent creates a 1/1 blue Tentacle creature token.
Whenever Harried Submersible deals combat damage to a player or planeswalker, draw a card.
Crew 2 (Tap any number of creatures you control with total power 2 or greater: This Vehicle becomes an artifact creature until end of turn.)

Field of Obelisks enters tapped.
As Field of Obelisks enters, choose a color other than white.
{T}: Add {W} or one mana of the chosen color.

Menace (This creature can't be blocked except by two or more creatures.)
Itava Warshrieker attacks each combat if able.

When Archive Guardian enters, return target card from your graveyard to your hand.
Recite {1}{B}{G} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Cast a copy of target creature or Revelation card in your graveyard without paying its mana cost. If a Revelation is cast this way, it enters as a Horror creature after it resolves.
Exile Wish to See.

Macabre Pools enters tapped. When it enters, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)
{T}: Add {U} or {B}.