Curse of Bloodletting

Enchant player
If a source would deal damage to enchanted player, it deals double that damage to that player instead.

Remorseless Punishment

Target opponent loses 5 life unless that player discards two cards or sacrifices a creature or planeswalker. Repeat this process once.

Commander's Sphere

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

Jaya's Immolating Inferno

(You may cast a legendary sorcery only if you control a legendary creature or planeswalker.)
Jaya's Immolating Inferno deals X damage to each of up to three targets.

Temple of Malice

Temple of Malice enters the battlefield tapped.
When Temple of Malice enters the battlefield, scry 1.
{T}: Add {B} or {R}.

Blisterspit Gremlin

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

Servant of Tymaret

Inspired — Whenever Servant of Tymaret becomes untapped, each opponent loses 1 life. You gain life equal to the life lost this way.
{2}{B}: Regenerate Servant of Tymaret.

Wound Reflection

At the beginning of each end step, each opponent loses life equal to the life they lost this turn. (Damage causes loss of life.)

Dragon's Claw

Whenever a player casts a red spell, you may gain 1 life.

Command Tower

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

Myriad Landscape

Myriad Landscape enters the battlefield tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Rummaging Goblin

Thrill of Possibility

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

Fire Servant

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

Fated Conflagration

Fated Conflagration deals 5 damage to target creature or planeswalker. If it's your turn, scry 2. (Look at the top two cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.)

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.

Scab-Clan Berserker

Haste
Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
Whenever an opponent casts a noncreature spell, if Scab-Clan Berserker is renowned, Scab-Clan Berserker deals 2 damage to that player.

Chandra, Torch of Defiance

+1: Exile the top card of your library. You may cast that card. If you don't, Chandra, Torch of Defiance deals 2 damage to each opponent.
+1: Add {R}{R}.
−3: Chandra, Torch of Defiance deals 4 damage to target creature.
−7: You get an emblem with "Whenever you cast a spell, this emblem deals 5 damage to any target."

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Pyretic Ritual

Arcane Signet

Triskelion

Triskelion enters the battlefield with three +1/+1 counters on it.
Remove a +1/+1 counter from Triskelion: It deals 1 damage to any target.

Dualcaster Mage

Flash
When Dualcaster Mage enters the battlefield, copy target instant or sorcery spell. You may choose new targets for the copy.

Infectious Curse

Enchant player
Spells you cast that target enchanted player cost {1} less to cast.
At the beginning of enchanted player's upkeep, that player loses 1 life and you gain 1 life.

Accursed Witch

Spells your opponents cast that target Accursed Witch cost {1} less to cast.
When Accursed Witch dies, return it to the battlefield transformed under your control attached to target opponent.

Accursed Witch // Infectious Curse

Howling Mine

At the beginning of each player's draw step, if Howling Mine is untapped, that player draws an additional card.

Bloodfire Kavu

{R}, Sacrifice Bloodfire Kavu: It deals 2 damage to each creature.

Explorer's Scope

Whenever equipped creature attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Roiling Vortex

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

Neheb, Dreadhorde Champion

Trample
Whenever Neheb, Dreadhorde Champion deals combat damage to a player or planeswalker, you may discard any number of cards. If you do, draw that many cards and add that much {R}. Until end of turn, you don't lose this mana as steps and phases end.

Damping Sphere

If a land is tapped for two or more mana, it produces {C} instead of any other type and amount.
Each spell a player casts costs {1} more to cast for each other spell that player has cast this turn.

Expedite

Target creature gains haste until end of turn.
Draw a card.

Sol Ring

Isolation Cell

Whenever an opponent casts a creature spell, that player loses 2 life unless they pay {2}.

Curse of the Pierced Heart

Enchant player
At the beginning of enchanted player's upkeep, Curse of the Pierced Heart deals 1 damage to that player or a planeswalker that player controls.

Macabre Waltz

Return up to two target creature cards from your graveyard to your hand, then discard a card.

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.

Havoc Festival

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

Shock

Tramway Station

Tramway Station enters the battlefield tapped.
{T}: Add {B} or {R}.
{2}{B}{R}, {T}, Sacrifice Tramway Station: Draw a card.

Professional Face-Breaker

Menace
Whenever one or more creatures you control deal combat damage to a player, create a Treasure token.
Sacrifice a Treasure: Exile the top card of your library. You may play that card this turn.

Possibility Storm

Whenever a player casts a spell from their hand, that player exiles it, then exiles cards from the top of their library until they exile a card that shares a card type with it. That player may cast that card without paying its mana cost. Then they put all cards exiled with Possibility Storm on the bottom of their library in a random order.

Killing Wave

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

Dark Dabbling

Regenerate target creature. Draw a card. (The next time the creature would be destroyed this turn, it isn't. Instead tap it, remove all damage from it, and remove it from combat.)
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, also regenerate each other creature you control.

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Hammerfist Giant

{T}: Hammerfist Giant deals 4 damage to each creature without flying and each player.

Jaya, Fiery Negotiator

+1: Create a 1/1 red Monk creature token with prowess.
−1: Exile the top two cards of your library. Choose one of them. You may play that card this turn.
−2: Choose target creature an opponent controls. Whenever you attack this turn, Jaya, Fiery Negotiator deals damage equal to the number of attacking creatures to that creature.
−8: You get an emblem with "Whenever you cast a red instant or sorcery spell, copy it twice. You may choose new targets for the copies."

Mountain

Kaervek, the Spiteful

Scheming Symmetry

Choose two target players. Each of them searches their library for a card, then shuffles and puts that card on top.

Mind Stone

{T}: Add {C}.
{1}, {T}, Sacrifice Mind Stone: Draw a card.

Kaervek the Merciless

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

Guttersnipe

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

Underworld Dreams

Whenever an opponent draws a card, Underworld Dreams deals 1 damage to that player.

Final Flare

As an additional cost to cast this spell, sacrifice a creature or enchantment.
Final Flare deals 5 damage to target creature.

Zo-Zu the Punisher

Whenever a land enters the battlefield, Zo-Zu the Punisher deals 2 damage to that land's controller.

Thriving Bluff

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

Lobber Crew

Defender
{T}: Lobber Crew deals 1 damage to each opponent.
Whenever you cast a multicolored spell, untap Lobber Crew.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Swamp

Swiftfoot Boots

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Quicksmith Rebel

When Quicksmith Rebel enters the battlefield, target artifact you control gains "{T}: This artifact deals 2 damage to any target" for as long as you control Quicksmith Rebel.

Burning Earth

Whenever a player taps a nonbasic land for mana, Burning Earth deals 1 damage to that 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.

Wild Ricochet

You may choose new targets for target instant or sorcery spell. Then copy that spell. You may choose new targets for the copy.

Ancient Runes

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

Lavaborn Muse

At the beginning of each opponent's upkeep, if that player has two or fewer cards in hand, Lavaborn Muse deals 3 damage to that player.

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.

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.)

Chandra's Phoenix

Flying
Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever an opponent is dealt damage by a red instant or sorcery spell you control or by a red planeswalker you control, return Chandra's Phoenix from your graveyard to your hand.

Phyrexian Arena

At the beginning of your upkeep, you draw a card and you lose 1 life.

Grim Lavamancer

{R}, {T}, Exile two cards from your graveyard: Grim Lavamancer deals 2 damage to any target.