Black Dragon

Flying
Acid Breath — When this creature enters, target creature an opponent controls gets -3/-3 until end of turn.

Have

Hall of Oracles

{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{T}: Put a +1/+1 counter on target creature. Activate only as a sorcery and only if you've cast an instant or sorcery spell this turn.

Splatter Goblin

When this creature dies, target creature an opponent controls gets -1/-1 until end of turn.

Zof Bloodbog

Zof Consumption

Each opponent loses 4 life and you gain 4 life.

Zof Consumption // Zof Bloodbog

Trench Stalker

As long as you've drawn two or more cards this turn, this creature has deathtouch and lifelink.

Argivian Avenger

{1}: Until end of turn, this creature gets -1/-1 and gains your choice of flying, vigilance, deathtouch, or haste.

Swamp

Baneclaw Marauder

Whenever this creature becomes blocked, each creature blocking it gets -1/-1 until end of turn.
Whenever a creature blocking this creature dies, that creature's controller loses 1 life.
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Baneblade Scoundrel

Whenever this creature becomes blocked, each creature blocking it gets -1/-1 until end of turn.
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Baneblade Scoundrel // Baneclaw Marauder

Stalking Predator

Menace (This creature can't be blocked except by two or more creatures.)
Nightbound (If a player casts at least two spells during their own turn, it becomes day next turn.)

Shady Traveler

Menace (This creature can't be blocked except by two or more creatures.)
Daybound (If a player casts no spells during their own turn, it becomes night next turn.)

Shady Traveler // Stalking Predator

Eyes of the Beholder

Target creature gets -11/-11 until end of turn.

Gruesome Realization

Choose one —
• You draw two cards and you lose 2 life.
• Creatures your opponents control get -1/-1 until end of turn.

Varragoth, Bloodsky Sire

Deathtouch
Boast — {1}{B}: Target player searches their library for a card, then shuffles and puts that card on top. (Activate only if this creature attacked this turn and only once each turn.)

Disfigure

Target creature gets -2/-2 until end of turn.

Introduction to Annihilation

Exile target nonland permanent. Its controller draws a card.

Dreadhound

When this creature enters, mill three cards. (Put the top three cards of your library into your graveyard.)
Whenever a creature dies or a creature card is put into a graveyard from a library, each opponent loses 1 life.

Gnawing Vermin

When this creature enters, target player mills two cards.
When this creature dies, target creature you don't control gets -1/-1 until end of turn.

Malicious Malfunction

All creatures get -2/-2 until end of turn. If a creature would die this turn, exile it instead.