msem-instigator

Abandoned Chamber enters with X story counters on it.
{3}, {T}, Remove all story counters from Abandoned Chamber and exile it: Return a card from your graveyard to your hand for each counter removed this way.

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)

Nonland permanents have “This permanent doesn't untap during your untap step” and “{2}: Untap this permanent.”

All creatures get -4/-4 until end of turn. If a creature would die this turn, exile it instead.

When Abaran enters, put a -1/-1 counter on up to one target creature.
At the beginning of your upkeep, if you control a creature with the greatest toughness among creatures on the battlefield, each opponent discards a card.

Up to one target creature gets +1/+1 and gains trample until end of turn. Put a -1/-1 counter on up to one target blocking or blocked creature.

Whenever you cast your first noncreature spell each turn, you may cast a creature spell with lesser mana value from your hand without paying its mana cost.
Whenever you attack with three or more creatures, target instant or sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.

When Abberant Frostbringer enters, 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.)

{1}, Sacrifice Aberrant Apostle: Choose one. This ability costs {1} less to activate as long as Aberrant Apostle entered this turn.
• Destroy target artifact.
• Destroy target enchantment.
• Exile target card from a graveyard.

Skip your draw step.
Your maximum hand size is equal to Abhorrent Academic's power.
At the beginning of your upkeep, if you have fewer cards in your hand than your maximum hand size, draw cards equal to the difference.

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, 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.

Put a +1/+1 counter on target creature. Prevent all combat damage other creatures would deal this turn.

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.

Counter target activated ability from a nonland source. (Mana abilities can't be targeted.)
Lifecycle {3} ({3}, Discard this card: Create two tapped 1/1 colorless Elemental creature tokens.)

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.

Menace
When this creature enters or dies, each opponent creates a 1/2 green Scout creature token.
{B}{G}, Discard this card: Distribute two -1/-1 counters among one or two target creatures. Activate only as a sorcery.

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

Destroy target creature with power 4 or greater. You gain 2 life.

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.