msem-instigator

Abandoned Laboratory enters the battlefield tapped if you control another nonbasic land.
{T}: Add {W} or {B}.

Abandoned Meadow enters the battlefield tapped if you control another nonbasic land.
{T}: Add {R} or {G}.

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

{T}: Add one mana of any color. If you control another nonbasic land, Abandoned Monument doesn't untap at the beginning of your next untap step.

Abandoned Preserve enters the battlefield tapped if you control another nonbasic land.
{T}: Add {B} or {G}.

{T}: Add {C}.
{3}, {T}, Sacrifice Abandoned Sanctuary: Search your library for a land card with a basic land type and put it onto the battlefield tapped, then shuffle.

Abandoned Shores enters the battlefield tapped if you control another nonbasic land.
{T}: Add {G} or {U}.

Abandoned Skyroad enters the battlefield tapped if you control another nonbasic land.
{T}: Add {W} or {U}.

Abandoned Wilderness enters the battlefield tapped if you control another nonbasic land.
{T}: Add {G} or {W}.

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

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.)

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 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.

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.

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 enters the battlefield under your control, 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.