Clawing Torment

Enchant artifact or creature
As long as enchanted permanent is a creature, it gets -1/-1 and can't block.
Enchanted permanent has "At the beginning of your upkeep, you lose 1 life."

Depressurize

Target creature gets -3/-0 until end of turn. Then if that creature's power is 0 or less, destroy it.

Lethal Exploit

Target creature gets -2/-2 until end of turn. It gets an additional -1/-1 until end of turn for each modified creature you controlled as you cast this spell. (Equipment, Auras you control, and counters are modifications.)

Languish

All creatures get -4/-4 until end of turn.

Stab

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

Wither and Bloom

Target creature gets -3/-3 until end of turn.
{1}{B}, Exile this card from your graveyard: Put a +1/+1 counter on target creature you control. Activate only as a sorcery.

Subtle Strike

Choose one or both —
• Target creature gets -1/-1 until end of turn.
• Put a +1/+1 counter on target creature.

Dead Weight

Enchant creature
Enchanted creature gets -2/-2.

Grim Bauble

When this artifact enters, target creature an opponent controls gets -2/-2 until end of turn.
{2}{B}, {T}, Sacrifice this artifact: Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Shefet Archfiend

Flying
When this creature enters, all other creatures get -2/-2 until end of turn.
Cycling {2} ({2}, Discard this card: Draw a card.)

Poison the Waters

Choose one —
• All creatures get -1/-1 until end of turn.
• Target player reveals their hand. You choose an artifact or creature card from it. That player discards that card.

Fear of Lost Teeth

When this creature dies, it deals 1 damage to any target and you gain 1 life.

Maximum Overdrive

Put a +1/+1 counter on target creature. It gains deathtouch and indestructible until end of turn.

Thieves' Guild Enforcer

Flash
Whenever this creature or another Rogue you control enters, each opponent mills two cards.
As long as an opponent has eight or more cards in their graveyard, this creature gets +2/+1 and has deathtouch.

Savor

Target creature gets -2/-2 until end of turn. Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")

Slice from the Shadows

This spell can't be countered. (This includes by the ward ability.)
Target creature gets -X/-X until end of turn.

Midnight Banshee

Wither (This deals damage to creatures in the form of -1/-1 counters.)
At the beginning of your upkeep, put a -1/-1 counter on each nonblack creature.

Winter's Intervention

Winter's Intervention deals 2 damage to target creature. You gain 2 life.

Moment of Craving

Target creature gets -2/-2 until end of turn. You gain 2 life.

Locust Spray

Target creature gets -1/-1 until end of turn.
Cycling {B} ({B}, Discard this card: Draw a card.)

Swamp

Kaervek, the Spiteful

Cruel Sadist

{B}, {T}, Pay 1 life: Put a +1/+1 counter on this creature.
{2}{B}, {T}, Remove X +1/+1 counters from this creature: It deals X damage to target creature.

Rage-Scarred Berserker

When this creature enters, target creature you control gets +1/+0 and gains indestructible until end of turn. (Damage and effects that say "destroy" don't destroy it.)

Killing Wave

For each creature, its controller sacrifices it unless they pay X life.

Syphon Fuel

Target creature gets -6/-6 until end of turn. You gain 2 life.

Skulking Killer

When this creature enters, target creature an opponent controls gets -2/-2 until end of turn if that opponent controls no other creatures.

Massacre Girl

Menace
When Massacre Girl enters, each other creature gets -1/-1 until end of turn. Whenever a creature dies this turn, each creature other than Massacre Girl gets -1/-1 until end of turn.

Biting Rain

All creatures get -2/-2 until end of turn.
Madness {2}{B} (If you discard this card, discard it into exile. When you do, cast it for its madness cost or put it into your graveyard.)

Drana, Kalastria Bloodchief

Flying
{X}{B}{B}: Target creature gets -0/-X until end of turn and Drana gets +X/+0 until end of turn.

Boarded Window

Creatures attacking you get -1/-0.
At the beginning of each end step, if you were dealt 4 or more damage this turn, exile this artifact.

Raffine's Silencer

When this creature enters, it connives. (Draw a card, then discard a card. If you discarded a nonland card, put a +1/+1 counter on this creature.)
When this creature dies, target creature an opponent controls gets -X/-X until end of turn, where X is this creature's power.

Mutilate

All creatures get -1/-1 until end of turn for each Swamp you control.

Throttle

Target creature gets -4/-4 until end of turn.

Curse of Death's Hold

Enchant player
Creatures enchanted player controls get -1/-1.

Massacre Girl, Known Killer

Menace
Creatures you control have wither. (They deal damage to creatures in the form of -1/-1 counters.)
Whenever a creature an opponent controls dies, if its toughness was less than 1, draw a card.

Miasma Demon

Flying
When this creature enters, you may discard any number of cards. When you do, up to that many target creatures each get -2/-2 until end of turn.

Drana, Liberator of Malakir

Flying, first strike
Whenever Drana deals combat damage to a player, put a +1/+1 counter on each attacking creature you control.

Deal Gone Bad

Target creature gets -3/-3 until end of turn. Target player mills three cards. (They put the top three cards of their library into their graveyard.)

Dismember

({B/P} can be paid with either {B} or 2 life.)
Target creature gets -5/-5 until end of turn.

Weigh Down

As an additional cost to cast this spell, exile a creature card from your graveyard.
Target creature gets -3/-3 until end of turn.

Flaying Tendrils

Devoid (This card has no color.)
All creatures get -2/-2 until end of turn. If a creature would die this turn, exile it instead.

Cackling Slasher

Deathtouch
This creature enters with a +1/+1 counter on it if a creature died this turn.