msem-instigator

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

Creature tokens you control have hexproof.
{3}{G}: Put a +1/+1 counter on target creature token.

Legendary spells you cast have nonlegendary cascade. (When you cast that spell, exile cards from the top of your library until you exile a nonlegendary nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Whenever you cast a noncreature spell, put a +1/+1 counter on Abjuration Savant. It gains flying until end of turn.
When Abjuration Savant dies, you gain life equal to its toughness.

At the beginning of your end step, you may pay {W}. If you do, exile target creature you control, then return that card to the battlefield under your control.

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.

Heretic (Whenever you cast a spell that doesn't share a color with this creature, it gets +1/+1 until end of turn.)
Discard a card: Abominable Mongrel gets +1/+1 and becomes the color of your choice until end of turn.

Trample
Whenever another Horror you control enters, put a +1/+1 counter on Abominable Xenoflora.

Menace
Whenever Abomination Blackguard deals combat damage to an opponent, you may draw a card. If you do, you lose 1 life.

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

When Abomination Emissary enters, target player mills six cards.

Abomination Sculptor has deathtouch and lifelink as long as it's attacking.

Whenever you make first contact, Abrasive Citizen gets +3/+0 until end of turn. (You make first contact the first time each turn you cast a spell with a name not in your graveyard or control already.)

[+1]: Create a 1/1 black Faerie creature token with flying and a 2/2 white Spirit Noble creature token with lifelink.
[–X]: Target creature gets -X/-X until end of turn. Its controller loses X life.
[–7]: You get an emblem with “Whenever a permanent you control enters, you may have it gain flying and vigilance and become a 4/4 Angel creature in addition to its other types.” (This effect lasts indefinitely.)

Protection from noncreatures and from creatures with power 3 or less
Players dealt damage by Absurdity also get that many poison counters. (A player with ten or more poison counters loses the game.)
When Absurdity is put into a graveyard from anywhere, shuffle it into its owner's library.

When Abura-no-Oni enters, target player mills two cards.

Abyss Howler must be blocked if able.
Whenever Abyss Howler becomes blocked, defending player loses 2 life and you gain 2 life.

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
Cycling {G} ({G}, Discard this card: Draw a card.)

Deathtouch
Abyss Surger enters with X +1/+1 counters on it, where X is the greatest power among creature cards in your graveyard.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
Abyssal Accuser must be blocked if able.

Haste
Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)

Abyssal Crypt enters tapped.
{T}: Add {U} or {B}.
{2}{U}{B}, {T}, Sacrifice Abyssal Crypt: Draw a card.

Wither (This deals damage to creatures in the form of -1/-1 counters.)
When Abyssal Familiar dies, it deals 1 damage to you and to any target.

When Abyssal Nightcaster enters, each player exiles a card from their hand.
When Abyssal Nightcaster dies, you may play cards you don't own from exile this turn.

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