msem-instigator

At the beginning of your upkeep, you may pay 2 life. If you do, crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)

Whenever a creature you control dies, put a +1/+1 counter on AOSE Xenocultivator. If this is the third time this ability resolved this turn, AOSE Xenocultivator deals 3 damage to any target.

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.

This spell costs {X} less to cast, where X is the greatest power among creatures you control.
Abandon Life and Hope deals 5 damage to target creature or planeswalker.

As an additional cost to cast this spell, discard a card.
Draw two cards. Forebode. (Create a tapped colorless Omen artifact token with “{T}, Discard a card, Sacrifice this artifact: Draw a card.”)

As an additional cost to cast this spell, sacrifice an artifact or creature.
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Counter target spell. If that spell is countered this way, put it on the bottom of its owner's library instead of putting it into its owner's graveyard. You may put up to three target cards from your graveyard on the bottom of your library in any order.

Abandoned Den enters tapped.
{T}: Add {B}.
{B}, {T}: Target player loses 1 life. Activate only as a sorcery and only if you control a black creature.

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

{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.

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.)

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.

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.

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.

When Abomination Emissary enters, target player mills six cards.

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

Destroy target creature or planeswalker.
Crystallize. (Put a +1/+1 counter on a creature you control or create a Treasure.)