msem-instigator

When 11-A Lionheart enters the battlefield, it deals 2 damage to each nonartifact creature.

Menace
Whenever you cycle A Most Important Prince or it attacks, each opponent with two or more cards in hand discards a card.
Basic landcycling {1}{B} ({1}{B}, Discard this card: Search your library for a basic land card, reveal it, and put it into your hand, then shuffle.)

Each player mills four cards.
Coalesce {5}{U}{U} (You may cast this from your graveyard for its coalesce cost. If you do, put it onto the battlefield as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
When A Vision Too Vast enters the battlefield, you may cast target noncreature, nonland card with mana value 4 or less from a graveyard without paying its mana cost.

Vigilance
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

Flying

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
{4}{B}{B}, {T}, Sacrifice Abalone Abomination: Create an X/X black Horror creature token, where X is the number of cards in your graveyard.

When Abberant Frostbringer enters the battlefield, tap up to one target creature. If you do, put two stun counters on that creature. (If a permanent with a stun counter would become untapped, remove one from it instead.)

At the beginning of your end step, if you're horrific, you draw a card and you lose life equal to the number of cards in your hand. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Engorge (As this enters the battlefield, mill three cards, then exile a card from among the milled cards.)
When Abhorrent Exhumer enters the battlefield, if it engorged a creature card, you may return target creature card from your graveyard to your hand.

Haste
Whenever Abominable Auteur attacks, you may return target creature card with mana value 3 or less from your graveyard to the battlefield. If that card's mana value was 1 or less, it enters tapped and attacking.

Trample
Whenever another Horror enters the battlefield under your control, put a +1/+1 counter on Abominable Xenoflora.

When Abomination Broodmother dies, create a 3/2 green Horror creature token.

{B}, {T}, Discard a card: Search your library for a card, then shuffle and put that card on top. You lose 2 life.

Whenever Abyssal Stalker attacks, defending player discards a card at random.
When Abyssal Stalker dies, you may choose a creature. If you do, exile Abyssal Stalker. When the chosen creature leaves the battlefield, return Abyssal Stalker from exile to the battlefield tapped.

Non-Human creatures you control get +1/+0.

Haste
This spell costs {2} less to cast if you've cast both an instant spell and a sorcery spell this turn.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
As you choose targets for an instant or sorcery spell, choose up to one additional target.
At the beginning of combat on your turn, gain control of another target creature until end of turn. Untap that creature. It gains haste until end of turn.

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.)

When Adamant Healer enters the battlefield, you may move any number of counters from target creature onto another target creature with the same controller.

{G}: Tap Adaptive Troll. It gains indestructible until end of turn.
At the beginning of each upkeep, if Adaptive Troll was dealt lethal damage last turn, put a counter of your choice on it from among vigilance, deathtouch, reach, trample, and +1/+1.

{T}: Adept Fisherman voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Adept Fisherman phases in, you gain 2 life.

Flash
When Adiran Distractor enters the battlefield, return up to one target creature you control and up to one target creature you don't control to their owners' hands.

As an additional cost to cast this spell, exile two permanent cards from your graveyard.
You may cast Adiran Survivors from your graveyard.

Whenever you cast a Pirate spell, create a 1/1 blue and red Pirate creature token with haste.

Menace
Whenever a creature an opponent controls dies, 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.”)