Heartless Hidetsugu

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

Silverclad Ferocidons

Enrage — Whenever this creature is dealt damage, each opponent sacrifices a permanent of their choice.

Bloodfire Dwarf

{R}, Sacrifice this creature: It deals 1 damage to each creature without flying.

Neheb, the Eternal

Afflict 3 (Whenever this creature becomes blocked, defending player loses 3 life.)
At the beginning of each of your postcombat main phases, add {R} for each 1 life your opponents have lost this turn.

Pestilent Spirit

Menace, deathtouch
Instant and sorcery spells you control have deathtouch. (Any amount of damage they deal to a creature is enough to destroy it.)

Sizzle

Obosh, the Preypiercer

Companion — Your starting deck contains only cards with odd mana values and land cards. (If this card is your chosen companion, you may put it into your hand from outside the game for {3} as a sorcery.)
If a source you control with an odd mana value would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Goblin Chainwhirler

First strike
When this creature enters, it deals 1 damage to each opponent and each creature and planeswalker they control.

Jaya, Venerated Firemage

If another red source you control would deal damage to a permanent or player, it deals that much damage plus 1 to that permanent or player instead.
−2: Jaya deals 2 damage to any target.

Fiery Cannonade

Fiery Cannonade deals 2 damage to each non-Pirate creature.

Angrath's Marauders

If a source you control would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Spellshock

Whenever a player casts a spell, this enchantment deals 2 damage to that player.

Chandra, Roaring Flame

+1: Chandra deals 2 damage to target player or planeswalker.
−2: Chandra deals 2 damage to target creature.
−7: Chandra deals 6 damage to each opponent. Each player dealt damage this way gets an emblem with "At the beginning of your upkeep, this emblem deals 3 damage to you."

Chandra, Fire of Kaladesh

Whenever you cast a red spell, untap Chandra.
{T}: Chandra deals 1 damage to target player or planeswalker. If Chandra has dealt 3 or more damage this turn, exile her, then return her to the battlefield transformed under her owner's control.

Chandra, Fire of Kaladesh // Chandra, Roaring Flame

Plague Spitter

At the beginning of your upkeep, this creature deals 1 damage to each creature and each player.
When this creature dies, it deals 1 damage to each creature and each player.

Everlasting Torment

Players can't gain life.
Damage can't be prevented.
All damage is dealt as though its source had wither. (A source with wither deals damage to creatures in the form of -1/-1 counters.)

Swamp

Succumb to Temptation

Urborg, Tomb of Yawgmoth

Each land is a Swamp in addition to its other land types.

The First Eruption

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I — This Saga deals 1 damage to each creature without flying.
II — Add {R}{R}.
III — Sacrifice a Mountain. If you do, this Saga deals 3 damage to each creature.

Dark Ritual

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Subterranean Spirit

Protection from red
{T}: This creature deals 1 damage to each creature without flying.

Flames of the Blood Hand

Flames of the Blood Hand deals 4 damage to target player or planeswalker. The damage can't be prevented. If that player or that planeswalker's controller would gain life this turn, that player gains no life instead.

Repercussion

Whenever a creature is dealt damage, this enchantment deals that much damage to that creature's controller.

Theater of Horrors

At the beginning of your upkeep, exile the top card of your library.
During your turn, if an opponent lost life this turn, you may play lands and cast spells from among cards exiled with this enchantment.
{3}{R}: This enchantment deals 1 damage to target opponent or planeswalker.

Dragonskull Summit

This land enters tapped unless you control a Swamp or a Mountain.
{T}: Add {B} or {R}.

Magus of the Wheel

{1}{R}, {T}, Sacrifice this creature: Each player discards their hand, then draws seven cards.

Quest for Pure Flame

Whenever a source you control deals damage to an opponent, you may put a quest counter on this enchantment.
Remove four quest counters from this enchantment and sacrifice it: If any source you control would deal damage to a permanent or player this turn, it deals double that damage to that permanent or player instead.

Syr Carah, the Bold

Whenever Syr Carah or an instant or sorcery spell you control deals damage to a player, exile the top card of your library. You may play that card this turn.
{T}: Syr Carah deals 1 damage to any target.

Blood Crypt

({T}: Add {B} or {R}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Banefire

Banefire deals X damage to any target.
If X is 5 or more, this spell can't be countered and the damage can't be prevented.

Volcanic Fallout

This spell can't be countered.
Volcanic Fallout deals 2 damage to each creature and each player.

Ob Nixilis, the Hate-Twisted

Whenever an opponent draws a card, Ob Nixilis deals 1 damage to that player.
−2: Destroy target creature. Its controller draws two cards.

Spear Spewer

Defender
{T}: This creature deals 1 damage to each player.

Rampaging Ferocidon

Menace
Players can't gain life.
Whenever another creature enters, this creature deals 1 damage to that creature's controller.

Gratuitous Violence

If a creature you control would deal damage to a permanent or player, it deals double that damage instead.

Rakdos Cluestone

{T}: Add {B} or {R}.
{B}{R}, {T}, Sacrifice this artifact: Draw a card.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Fire Ants

{T}: This creature deals 1 damage to each other creature without flying.

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Tremor

Tremor deals 1 damage to each creature without flying.

Magma Giant

When this creature enters, it deals 2 damage to each creature and each player.

Sweltering Suns

Sweltering Suns deals 3 damage to each creature.
Cycling {3} ({3}, Discard this card: Draw a card.)

Earthquake

Earthquake deals X damage to each creature without flying and each player.

Crypt Rats

{X}: This creature deals X damage to each creature and each player. Spend only black mana on X.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Aria of Flame

When this enchantment enters, each opponent gains 10 life.
Whenever you cast an instant or sorcery spell, put a verse counter on this enchantment, then it deals damage equal to the number of verse counters on it to target player or planeswalker.

Stuffy Doll

Indestructible
As this creature enters, choose a player.
Whenever this creature is dealt damage, it deals that much damage to the chosen player.
{T}: This creature deals 1 damage to itself.

Electrickery

Electrickery deals 1 damage to target creature you don't control.
Overload {1}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Tibalt, Rakish Instigator

Your opponents can't gain life.
−2: Create a 1/1 red Devil creature token with "When this token dies, it deals 1 damage to any target."

Arcbond

Choose target creature. Whenever that creature is dealt damage this turn, it deals that much damage to each other creature and each player.

Skewer the Critics

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Skewer the Critics deals 3 damage to any target.

Kazarov, Sengir Pureblood

Flying
Whenever a creature an opponent controls is dealt damage, put a +1/+1 counter on Kazarov.
{3}{R}: Kazarov deals 2 damage to target creature.

Commander's Sphere

{T}: Add one mana of any color in your commander's color identity.
Sacrifice this artifact: Draw a card.

Darksteel Plate

Indestructible
Equipped creature has indestructible.
Equip {2}

Caltrops

Whenever a creature attacks, this artifact deals 1 damage to it.

Rolling Earthquake

Rolling Earthquake deals X damage to each creature without horsemanship and each player.

Wail of the Nim

Choose one —
• Regenerate each creature you control.
• Wail of the Nim deals 1 damage to each creature and each player.
Entwine {B} (Choose both if you pay the entwine cost.)

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.)

Pyromancer's Gauntlet

If a red instant or sorcery spell you control or a red planeswalker you control would deal damage to a permanent or player, it deals that much damage plus 2 to that permanent or player instead.

Risk Factor

Target opponent may have Risk Factor deal 4 damage to them. If that player doesn't, you draw three cards.
Jump-start (You may cast this card from your graveyard by discarding a card in addition to paying its other costs. Then exile this card.)

Cinder Pyromancer

{T}: This creature deals 1 damage to target player or planeswalker.
Whenever you cast a red spell, you may untap this creature.

Mana Geyser

Add {R} for each tapped land your opponents control.

Bonfire of the Damned

Bonfire of the Damned deals X damage to target player or planeswalker and each creature that player or that planeswalker's controller controls.
Miracle {X}{R} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Fire Servant

If a red instant or sorcery spell you control would deal damage, it deals double that damage instead.

Dictate of the Twin Gods

Flash
If a source would deal damage to a permanent or player, it deals double that damage to that permanent or player instead.

Shock

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.

Inflame

Inflame deals 2 damage to each creature dealt damage this turn.

Bedevil

Destroy target artifact, creature, or planeswalker.

Shake the Foundations

Shake the Foundations deals 1 damage to each creature without flying.
Draw a card.

Chaos Maw

When this creature enters, it deals 3 damage to each other creature.

Mountain

Slagstorm

Choose one —
• Slagstorm deals 3 damage to each creature.
• Slagstorm deals 3 damage to each player.

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.

Thrashing Wumpus

{B}: This creature deals 1 damage to each creature and each player.

Anger of the Gods

Anger of the Gods deals 3 damage to each creature. If a creature dealt damage this way would die this turn, exile it instead.