Painful Quandary

Whenever an opponent casts a spell, that player loses 5 life unless they discard a card.

Imodane, the Pyrohammer

Whenever an instant or sorcery spell you control that targets only a single creature deals damage to that creature, Imodane deals that much damage to each opponent.

Bedevil

Destroy target artifact, creature, or planeswalker.

Havoc Festival

Players can't gain life.
At the beginning of each player's upkeep, that player loses half their life, rounded up.

Thrill of Possibility

As an additional cost to cast this spell, discard a card.
Draw two cards.

Roiling Vortex

At the beginning of each player's upkeep, this enchantment deals 1 damage to them.
Whenever a player casts a spell, if no mana was spent to cast that spell, this enchantment deals 5 damage to that player.
{R}: Your opponents can't gain life this turn.

Coalhauler Swine

Whenever this creature is dealt damage, it deals that much damage to each player.

Cutthroat Contender

Pay 1 life: This creature gets +1/+0 until end of turn. Activate only once each turn.

Kaervek the Merciless

Whenever an opponent casts a spell, Kaervek deals damage equal to that spell's mana value to any target.

Kaervek, the Spiteful

Browbeat

Any player may have Browbeat deal 5 damage to them. If no one does, target player draws three cards.

Spiteflame Witch

Crushing Disappointment

Each player loses 2 life. You draw two cards.

Fire Diamond

This artifact enters tapped.
{T}: Add {R}.

Stormfist Crusader

Menace
At the beginning of your upkeep, each player draws a card and loses 1 life.

Wall of Blood

Defender (This creature can't attack.)
Pay 1 life: This creature gets +1/+1 until end of turn.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Swamp

Dire Fleet Ravager

Menace, deathtouch
When this creature enters, each player loses a third of their life, rounded up.

Assault on Osgiliath

Amass Orcs X, then Goblins and Orcs you control gain double strike and haste until end of turn. (To amass Orcs X, put X +1/+1 counters on an Army you control. It's also an Orc. If you don't control an Army, create a 0/0 black Orc Army creature token first.)

Blood-Toll Harpy

Flying
When this creature enters, each player loses 1 life.

Talisman of Indulgence

{T}: Add {C}.
{T}: Add {B} or {R}. This artifact deals 1 damage to you.

Charcoal Diamond

This artifact enters tapped.
{T}: Add {B}.

Comet Storm

Multikicker {1} (You may pay an additional {1} any number of times as you cast this spell.)
Choose any target, then choose another target for each time this spell was kicked. Comet Storm deals X damage to each of them.

Rakdos's Return

Rakdos's Return deals X damage to target opponent or planeswalker. That player or that planeswalker's controller discards X cards.

Myr Convert

Toxic 1 (Players dealt combat damage by this creature also get a poison counter.)
{T}, Pay 2 life: Add one mana of any color.

Repay in Kind

Each player's life total becomes the lowest life total among all players.

Read the Bones

Scry 2, then draw two cards. You lose 2 life. (To scry 2, look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Blood Celebrant

{B}, Pay 1 life: Add one mana of any color.

Fire Covenant

As an additional cost to cast this spell, pay X life.
Fire Covenant deals X damage divided as you choose among any number of target creatures.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Syr Konrad, the Grim

Whenever another creature dies, or a creature card is put into a graveyard from anywhere other than the battlefield, or a creature card leaves your graveyard, Syr Konrad deals 1 damage to each opponent.
{1}{B}: Each player mills a card. (They each put the top card of their library into their graveyard.)

Ambition's Cost

You draw three cards and you lose 3 life.

Flame Rift

Flame Rift deals 4 damage to each player.

Moltensteel Dragon

({R/P} can be paid with either {R} or 2 life.)
Flying
{R/P}: This creature gets +1/+0 until end of turn.

Rivalry

At the beginning of each player's upkeep, if that player controls more lands than each other player, this enchantment deals 2 damage to them.

In Garruk's Wake

Destroy all creatures you don't control and all planeswalkers you don't control.

Damnable Pact

Target player draws X cards and loses X life.

Rowan, Scion of War

Menace
{T}: Spells you cast this turn that are black and/or red cost {X} less to cast, where X is the amount of life you lost this turn. Activate only as a sorcery.

Sulfurous Springs

{T}: Add {C}.
{T}: Add {B} or {R}. This land deals 1 damage to you.

Sulfuric Vortex

At the beginning of each player's upkeep, this enchantment deals 2 damage to that player.
If a player would gain life, that player gains no life instead.

Night's Whisper

Crackle with Power

Crackle with Power deals five times X damage to each of up to X targets.

Profane Transfusion

Two target players exchange life totals. You create an X/X colorless Horror artifact creature token, where X is the difference between those players' life totals.

Seizan, Perverter of Truth

At the beginning of each player's upkeep, that player loses 2 life and draws two cards.

Ancient Runes

At the beginning of each player's upkeep, this enchantment deals damage to that player equal to the number of artifacts they control.

Maggot Carrier

When this creature enters, each player loses 1 life.

Mountain

Exsanguinate

Each opponent loses X life. You gain life equal to the life lost this way.

Sol Ring

Fireball

This spell costs {1} more to cast for each target beyond the first.
Fireball deals X damage divided evenly, rounded down, among any number of targets.

Descent into Avernus

At the beginning of your upkeep, put two descent counters on this enchantment. Then each player creates X Treasure tokens and this enchantment deals X damage to each player, where X is the number of descent counters on this enchantment.

Tavern Swindler

{T}, Pay 3 life: Flip a coin. If you win the flip, you gain 6 life.

Soulcage Fiend

When this creature dies, each player loses 3 life.

Sign in Blood

Target player draws two cards and loses 2 life.

Acidic Soil

Acidic Soil deals damage to each player equal to the number of lands they control.

Zhentarim Bandit

Whenever this creature attacks, you may pay 1 life. If you do, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")