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.

End the Festivities

End the Festivities deals 1 damage to each opponent and each creature and planeswalker they control.

Mountain

Trouble

Trouble deals damage to target player equal to the number of cards in that player's hand.
Fuse (You may cast one or both halves of this card from your hand.)

Toil

Target player draws two cards and loses 2 life.
Fuse (You may cast one or both halves of this card from your hand.)

Toil // Trouble

Runaway Steam-Kin

Whenever you cast a red spell, if Runaway Steam-Kin has fewer than three +1/+1 counters on it, put a +1/+1 counter on Runaway Steam-Kin.
Remove three +1/+1 counters from Runaway Steam-Kin: Add {R}{R}{R}.

Mana Geyser

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

Wizard's Lightning

This spell costs {2} less to cast if you control a Wizard.
Wizard's Lightning deals 3 damage to any target.

Viashino Pyromancer

When Viashino Pyromancer enters the battlefield, it deals 2 damage to target player or planeswalker.

Electrostatic Field

Defender
Whenever you cast an instant or sorcery spell, Electrostatic Field deals 1 damage to each opponent.

Stomp

Damage can't be prevented this turn. Stomp deals 2 damage to any target.

Bonecrusher Giant

Whenever Bonecrusher Giant becomes the target of a spell, Bonecrusher Giant deals 2 damage to that spell's controller.

Bonecrusher Giant // Stomp

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Flame-Blessed Bolt

Flame-Blessed Bolt deals 2 damage to target creature or planeswalker. If that creature or planeswalker would die this turn, exile it instead.

You Are Already Dead

Destroy target creature that was dealt damage this turn.
Draw a card.

Syr Carah, the Bold

Whenever Syr Carah, the Bold 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.

Thermo-Alchemist

Defender
{T}: Thermo-Alchemist deals 1 damage to each opponent.
Whenever you cast an instant or sorcery spell, untap Thermo-Alchemist.

Nightscape Familiar

Blue spells and red spells you cast cost {1} less to cast.
{1}{B}: Regenerate Nightscape Familiar.

Forktail Sweep

Forktail Sweep deals 1 damage to each creature you don't control. (Then exile this card. You may cast the creature later from exile.)

Fang Dragon

Fang Dragon // Forktail Sweep

Cliffgate

Cliffgate enters the battlefield tapped.
As Cliffgate enters the battlefield, choose a color other than red.
{T}: Add {R} or one mana of the chosen color.

Kessig Flamebreather

Whenever you cast a noncreature spell, Kessig Flamebreather deals 1 damage to each opponent.

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.

Forked Bolt

Forked Bolt deals 2 damage divided as you choose among one or two targets.

Shock

Lightning Strike

Lightning Strike deals 3 damage to any target.

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

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.

Creeping Bloodsucker

At the beginning of your upkeep, Creeping Bloodsucker deals 1 damage to each opponent. You gain life equal to the damage dealt this way.

Black Dragon Gate

Black Dragon Gate enters the battlefield tapped.
As Black Dragon Gate enters the battlefield, choose a color other than black.
{T}: Add {B} or one mana of the chosen color.

Guttersnipe

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

Have

Orcish Bowmasters

Flash
When Orcish Bowmasters enters the battlefield and whenever an opponent draws a card except the first one they draw in each of their draw steps, Orcish Bowmasters deals 1 damage to any target. Then amass Orcs 1.

Firebrand Archer

Whenever you cast a noncreature spell, Firebrand Archer deals 1 damage to each opponent.

Rakdos Guildgate

Rakdos Guildgate enters the battlefield tapped.
{T}: Add {B} or {R}.

Backdraft Hellkite

Flying
Whenever Backdraft Hellkite attacks, each instant and sorcery card in your graveyard gains flashback until end of turn. The flashback cost is equal to its mana cost.

Volcanic Fallout

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

Tor Wauki the Younger

Reach, lifelink
If another source you control would deal noncombat damage to a permanent or player, it deals that much damage plus 1 to that permanent or player instead.
Whenever you cast an instant or sorcery spell, Tor Wauki the Younger deals 2 damage to any target.

Glittering Stockpile

{T}: Add {R}. Put a stash counter on Glittering Stockpile.
{T}, Sacrifice Glittering Stockpile: Add X mana of any one color, where X is the number of stash counters on Glittering Stockpile.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Sulfuric Vortex

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

Fire Prophecy

Fire Prophecy deals 3 damage to target creature. You may put a card from your hand on the bottom of your library. If you do, draw a card.

Damnable Pact

Target player draws X cards and loses X life.

Grapeshot

Grapeshot deals 1 damage to any target.
Storm (When you cast this spell, copy it for each spell cast before it this turn. You may choose new targets for the copies.)

Sign in Blood

Target player draws two cards and loses 2 life.

Rakdos Signet

Harsh Mentor

Whenever an opponent activates an ability of an artifact, creature, or land on the battlefield, if it isn't a mana ability, Harsh Mentor deals 2 damage to that player.

Fiery Inscription

When Fiery Inscription enters the battlefield, the Ring tempts you.
Whenever you cast an instant or sorcery spell, Fiery Inscription deals 2 damage to each opponent.

Ill-Gotten Inheritance

At the beginning of your upkeep, Ill-Gotten Inheritance deals 1 damage to each opponent and you gain 1 life.
{5}{B}, Sacrifice Ill-Gotten Inheritance: It deals 4 damage to target opponent and you gain 4 life.

Sol Ring

Cinder Pyromancer

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

Lava Dart

Lava Dart deals 1 damage to any target.
Flashback—Sacrifice a Mountain. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Foreboding Fruit

Target player draws two cards and loses 2 life.
Adamant — If at least three black mana was spent to cast this spell, create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.")

Sawblade Scamp

Haste
Whenever you cast a noncreature spell, put an oil counter on Sawblade Scamp.
{T}, Remove an oil counter from Sawblade Scamp: It deals 1 damage to each opponent.

Command Tower

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

Tectonic Hazard

Tectonic Hazard deals 1 damage to each opponent and each creature they control.

Mizzium Mortars

Mizzium Mortars deals 4 damage to target creature you don't control.
Overload {3}{R}{R}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Prodigal Pyromancer

{T}: Prodigal Pyromancer deals 1 damage to any target.

Fire Servant

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

Spear Spewer

Defender
{T}: Spear Spewer deals 1 damage to each player.

Light Up the Stage

Spectacle {R} (You may cast this spell for its spectacle cost rather than its mana cost if an opponent lost life this turn.)
Exile the top two cards of your library. Until the end of your next turn, you may play those cards.

Blazing Volley

Blazing Volley deals 1 damage to each creature your opponents control.

Manabarbs

Whenever a player taps a land for mana, Manabarbs deals 1 damage to that player.

Arc Lightning

Arc Lightning deals 3 damage divided as you choose among one, two, or three targets.

Mechanized Warfare

If a red or artifact source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 1 instead.

Rakdos Charm

Choose one —
• Exile target player's graveyard.
• Destroy target artifact.
• Each creature deals 1 damage to its controller.

Syphon Soul

Syphon Soul deals 2 damage to each other player. You gain life equal to the damage dealt this way.

Abrade

Choose one —
• Abrade deals 3 damage to target creature.
• Destroy target artifact.

Seething Song

Blisterspit Gremlin

{1}, {T}: Blisterspit Gremlin deals 1 damage to each opponent.
Whenever you cast a noncreature spell, untap Blisterspit Gremlin.

Fiery Impulse

Fiery Impulse deals 2 damage to target creature.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, Fiery Impulse deals 3 damage instead.

Erebor Flamesmith

Whenever you cast an instant or sorcery spell, Erebor Flamesmith deals 1 damage to each opponent.

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.")

Swamp

Pestilence

At the beginning of the end step, if no creatures are on the battlefield, sacrifice Pestilence.
{B}: Pestilence deals 1 damage to each creature and each player.

Torbran, Thane of Red Fell

If a red source you control would deal damage to an opponent or a permanent an opponent controls, it deals that much damage plus 2 instead.