Runaway Steam-Kin

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

Castle Embereth

This land enters tapped unless you control a Mountain.
{T}: Add {R}.
{1}{R}{R}, {T}: Creatures you control get +1/+0 until end of turn.

Faithless Looting

Draw two cards, then discard two cards.
Flashback {2}{R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Glitterfang

Haste
At the beginning of the end step, return this creature to its owner's hand.

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.

Cinder Pyromancer

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

Confusion in the Ranks

Whenever an artifact, creature, or enchantment enters, its controller chooses target permanent another player controls that shares a card type with it. Exchange control of those permanents.

Gauntlets of Chaos

{5}, Sacrifice this artifact: Exchange control of target artifact, creature, or land you control and target permanent an opponent controls that shares one of those types with it. If those permanents are exchanged this way, destroy all Auras attached to them.

Horn of Plenty

Whenever a player casts a spell, they may pay {1}. If the player does, they draw a card at the beginning of the next end step.

Ogre Battledriver

Whenever another creature you control enters, that creature gets +2/+0 and gains haste until end of turn. (It can attack and {T} this turn.)

Hazoret's Monument

Red creature spells you cast cost {1} less to cast.
Whenever you cast a creature spell, you may discard a card. If you do, draw a card.

Ardoz, Cobbler of War

Haste
Whenever Ardoz or another creature you control enters, that creature gets +2/+0 until end of turn.
{3}{R}: Create a 1/1 red Goblin creature token with haste. Activate only as a sorcery.

Cathartic Pyre

Choose one —
• Cathartic Pyre deals 3 damage to target creature or planeswalker.
• Discard up to two cards, then draw that many cards.

Sokenzan, Crucible of Defiance

{T}: Add {R}.
Channel — {3}{R}, Discard this card: Create two 1/1 colorless Spirit creature tokens. They gain haste until end of turn. This ability costs {1} less to activate for each legendary creature you control.

Symmetry Matrix

Whenever a creature you control with power equal to its toughness enters, you may pay {1}. If you do, draw a card.

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

Fire Diamond

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

Goblin Heelcutter

Whenever this creature attacks, target creature can't block this turn.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Dangerous Wager

Zenith Chronicler

Whenever a player casts their first multicolored spell each turn, each other player draws a card.

Kolaghan Forerunners

Trample
Kolaghan Forerunners's power is equal to the number of creatures you control.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Diamond Knight

Vigilance (Attacking doesn't cause this creature to tap.)
As this creature enters, choose a color.
Whenever you cast a spell of the chosen color, put a +1/+1 counter on this creature.

Blasphemous Act

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

Noetic Scales

At the beginning of each player's upkeep, return to its owner's hand each creature that player controls with power greater than the number of cards in their hand.

Red Elemental Blast

Choose one —
• Counter target blue spell.
• Destroy target blue permanent.

Wheel of Fate

Suspend 4—{1}{R} (Rather than cast this card from your hand, pay {1}{R} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Each player discards their hand, then draws seven cards.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Refraction Elemental

Ward—Pay 2 life.
Whenever you cast a spell, this creature deals 2 damage to each opponent.

Invasion of Karsus

(As a Siege enters, choose an opponent to protect it. You and others can attack it. When it's defeated, exile it, then cast it transformed.)
When this Siege enters, it deals 3 damage to each creature and each planeswalker.

Invasion of Karsus // Refraction Elemental

Wild Magic Surge

Destroy target permanent an opponent controls. Its controller reveals cards from the top of their library until they reveal a permanent card that shares a card type with that permanent. They put that card onto the battlefield and the rest on the bottom of their library in a random order.

War Room

{T}: Add {C}.
{3}, {T}, Pay life equal to the number of colors in your commanders' color identity: Draw a card.

Hour of Devastation

All creatures lose indestructible until end of turn. Hour of Devastation deals 5 damage to each creature and each non-Bolas planeswalker.

Furious Assault

Whenever you cast a creature spell, this enchantment deals 1 damage to target player or planeswalker.

Vaultbreaker

Whenever this creature attacks, you may discard a card. If you do, draw a card.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Defiler of Instinct

First strike
As an additional cost to cast red permanent spells, you may pay 2 life. Those spells cost {R} less to cast if you paid life this way. This effect reduces only the amount of red mana you pay.
Whenever you cast a red permanent spell, this creature deals 1 damage to any target.

Mountain

Knowledge Pool

Imprint — When this artifact enters, each player exiles the top three cards of their library.
Whenever a player casts a spell from their hand, that player exiles it. If the player does, they may cast a spell from among other cards exiled with this artifact without paying its mana cost.

Magmatic Sprinter

Haste
When this creature enters, put two oil counters on target artifact or creature you control.
At the beginning of your end step, return this creature to its owner's hand unless you remove two oil counters from it.

Shattering Pulse

Buyback {3} (You may pay an additional {3} as you cast this spell. If you do, put this card into your hand as it resolves.)
Destroy target artifact.

Flamekin Herald

Commander spells you cast have cascade. (Whenever you cast a commander, exile cards from the top of your library until you exile a nonland card with lesser mana value. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Rolling Earthquake

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

Impact Tremors

Whenever a creature you control enters, this enchantment deals 1 damage to each opponent.

Zurgo Bellstriker

Zurgo can't block creatures with power 2 or greater.
Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Thrill of Possibility

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

By Force

Goblin Battle Jester

Whenever you cast a red spell, target creature can't block this turn.

Pyroblast

Choose one —
• Counter target spell if it's blue.
• Destroy target permanent if it's blue.

Reinforced Ronin

Haste
At the beginning of your end step, return this creature to its owner's hand.
Channel — {1}{R}, Discard this card: Draw a card.

Foundry Street Denizen

Whenever another red creature you control enters, this creature gets +1/+0 until end of turn.

Lightning Berserker

{R}: This creature gets +1/+0 until end of turn.
Dash {R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Shatterskull Charger

Kicker {2}
Trample, haste
If this creature was kicked, it enters with a +1/+1 counter on it.
At the beginning of your end step, if this creature doesn't have a +1/+1 counter on it, return it to its owner's hand.

Intimidator Initiate

Whenever a player casts a red spell, you may pay {1}. If you do, target creature can't block this turn.

In the Web of War

Whenever a creature you control enters, it gets +2/+0 and gains haste until end of turn.

Chain Reaction

Chain Reaction deals X damage to each creature, where X is the number of creatures on the battlefield.

Viashino Sandstalker

Haste (This creature can attack and {T} as soon as it comes under your control.)
At the beginning of the end step, return this creature to its owner's hand. (Return it only if it's on the battlefield.)

Lightning Cloud

Whenever a player casts a red spell, you may pay {R}. If you do, this enchantment deals 1 damage to any target.

Warbringer

Dash costs you pay cost {2} less (as long as this creature is on the battlefield).
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Spitfire Bastion

(Transforms from Vance's Blasting Cannons.)
{T}: Add {R}.
{2}{R}, {T}: Spitfire Bastion deals 3 damage to any target.

Vance's Blasting Cannons

At the beginning of your upkeep, exile the top card of your library. If it's a nonland card, you may cast that card this turn.
Whenever you cast your third spell in a turn, you may transform Vance's Blasting Cannons.

Vance's Blasting Cannons // Spitfire Bastion

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Scavenger Grounds

{T}: Add {C}.
{2}, {T}, Sacrifice a Desert: Exile all graveyards.

Screamreach Brawler

Dash {1}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Arcane Signet

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

Scrappy Bruiser

Whenever this creature attacks, up to one target attacking creature gets +2/+0 and gains trample until end of turn. Return that creature to its owner's hand at end of combat. (Return it only if it's on the battlefield.)

Chaos Warp

The owner of target permanent shuffles it into their library, then reveals the top card of their library. If it's a permanent card, they put it onto the battlefield.

Viashino Sandsprinter

Trample, haste
At the beginning of the end step, return this creature to its owner's hand. (Return it only if it's on the battlefield.)
Cycling {R} ({R}, Discard this card: Draw a card.)