Shiny Impetus

Enchant creature
Enchanted creature gets +2/+2 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
Whenever enchanted creature attacks, you create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Molten Vortex

{R}, Discard a land card: Molten Vortex deals 2 damage to any target.

Earthquake

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

Spark Spray

Spark Spray deals 1 damage to any target.
Cycling {R} ({R}, Discard this card: Draw a card.)

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.)

Fractured Loyalty

Enchant creature
Whenever enchanted creature becomes the target of a spell or ability, that spell or ability's controller gains control of that creature. (This effect lasts indefinitely.)

Khârn the Betrayer

Berzerker — Khârn the Betrayer attacks or blocks each combat if able.
Sigil of Corruption — When you lose control of Khârn the Betrayer, draw two cards.
The Betrayer — If damage would be dealt to Khârn the Betrayer, prevent that damage and an opponent of your choice gains control of it.

Jaya Ballard, Task Mage

{R}, {T}, Discard a card: Destroy target blue permanent.
{1}{R}, {T}, Discard a card: Jaya Ballard, Task Mage deals 3 damage to any target. A creature dealt damage this way can't be regenerated this turn.
{5}{R}{R}, {T}, Discard a card: Jaya Ballard deals 6 damage to each creature and each player.

Coalhauler Swine

Whenever Coalhauler Swine is dealt damage, it deals that much damage to each player.

Flame Sweep

Flame Sweep deals 2 damage to each creature except for creatures you control with flying.

Knollspine Invocation

{X}, Discard a card with mana value X: Knollspine Invocation deals X damage to any target.

Runeflare Trap

If an opponent drew three or more cards this turn, you may pay {R} rather than pay this spell's mana cost.
Runeflare Trap deals damage to target player equal to the number of cards in that player's hand.

Grappling Hook

Equipped creature has double strike.
Whenever equipped creature attacks, you may have target creature block it this turn if able.
Equip {4}

Structural Assault

Destroy all artifacts, then Structural Assault deals damage to each creature equal to the number of artifacts that were put into graveyards from the battlefield this turn.

Lavaball Trap

If an opponent had two or more lands enter the battlefield under their control this turn, you may pay {3}{R}{R} rather than pay this spell's mana cost.
Destroy two target lands. Lavaball Trap deals 4 damage to each creature.

Flamekin Spitfire

{3}{R}: Flamekin Spitfire deals 1 damage to any target.

Homeward Path

{T}: Add {C}.
{T}: Each player gains control of all creatures they own.

Sweltering Suns

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

Stuffy Doll

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

Tibalt, Rakish Instigator

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

Fall of Cair Andros

Whenever a creature an opponent controls is dealt excess noncombat damage, amass Orcs X, where X is that excess damage. (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.)
{7}{R}: Fall of Cair Andros deals 7 damage to target creature.

Sudden Impact

Sudden Impact deals damage to target player equal to the number of cards in that player's hand.

Anaba Shaman

{R}, {T}: Anaba Shaman deals 1 damage to any target.

Star of Extinction

Destroy target land. Star of Extinction deals 20 damage to each creature and each planeswalker.

Vulshok Sorcerer

Haste
{T}: Vulshok Sorcerer deals 1 damage to any target.

Grim Lavamancer

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

Sticky Fingers

Enchant creature
Enchanted creature has menace and "Whenever this creature deals combat damage to a player, create a Treasure token." (It can't be blocked except by two or more creatures. The token is an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
When enchanted creature dies, draw a card.

Toggo, Goblin Weaponsmith

Landfall — Whenever a land you control enters, create a colorless Equipment artifact token named Rock with "Equipped creature has '{1}, {T}, Sacrifice Rock: This creature deals 2 damage to any target'" and equip {1}.
Partner (You can have two commanders if both have partner.)

Sudden Demise

Choose a color. Sudden Demise deals X damage to each creature of the chosen color.

Embermaw Hellion

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)
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.

Ashling the Pilgrim

{1}{R}: Put a +1/+1 counter on Ashling the Pilgrim. If this is the third time this ability has resolved this turn, remove all +1/+1 counters from Ashling the Pilgrim, and it deals that much damage to each creature and each player.

Beamtown Beatstick

Equipped creature gets +1/+0 and has menace. (It can't be blocked except by two or more creatures.)
Whenever equipped creature deals combat damage to a player or battle, create a Treasure token.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Ravaging Blaze

Ravaging Blaze deals X damage to target creature.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, Ravaging Blaze also deals X damage to that creature's controller.

Laccolith Rig

Enchant creature
Whenever enchanted creature becomes blocked, you may have it deal damage equal to its power to target creature. If you do, the first creature assigns no combat damage this turn.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Captain's Claws

Equipped creature gets +1/+0.
Whenever equipped creature attacks, create a 1/1 white Kor Ally creature token that's tapped and attacking.
Equip {1}

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.

Vow of Lightning

Enchant creature
Enchanted creature gets +2/+2, has first strike, and can't attack you or planeswalkers you control.

Fire Diamond

Fire Diamond enters tapped.
{T}: Add {R}.

Arcane Bombardment

Whenever you cast your first instant or sorcery spell each turn, exile an instant or sorcery card at random from your graveyard. Then copy each card exiled with Arcane Bombardment. You may cast any number of the copies without paying their mana costs.

Starstorm

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

Thought Vessel

You have no maximum hand size.
{T}: Add {C}.

Magma Phoenix

Flying
When Magma Phoenix dies, it deals 3 damage to each creature and each player.
{3}{R}{R}: Return Magma Phoenix from your graveyard to your hand.

Fiery Confluence

Choose three. You may choose the same mode more than once.
• Fiery Confluence deals 1 damage to each creature.
• Fiery Confluence deals 2 damage to each opponent.
• Destroy target artifact.

Ghirapur Aether Grid

Tap two untapped artifacts you control: Ghirapur Aether Grid deals 1 damage to any target.

Bloodthirsty Blade

Equipped creature gets +2/+0 and is goaded. (It attacks each combat if able and attacks a player other than you if able.)
{1}: Attach Bloodthirsty Blade to target creature an opponent controls. Activate only as a sorcery.

Pyroclasm

Pyroclasm deals 2 damage to each creature.

Chandra, Flamecaller

+1: Create two 3/1 red Elemental creature tokens with haste. Exile them at the beginning of the next end step.
0: Discard all the cards in your hand, then draw that many cards plus one.
−X: Chandra, Flamecaller deals X damage to each creature.

Mishra's Command

Choose two —
• Choose target player. They may discard up to X cards. Then they draw a card for each card discarded this way.
• This spell deals X damage to target creature.
• This spell deals X damage to target planeswalker.
• Target creature gets +X/+0 and gains haste until end of turn.

Thunderous Might

Enchant creature
Whenever enchanted creature attacks, it gets +X/+0 until end of turn, where X is your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)

Storm's Wrath

Storm's Wrath deals 4 damage to each creature and each planeswalker.

Vicious Shadows

Whenever a creature dies, you may have Vicious Shadows deal damage to target player equal to the number of cards in that player's hand.

Chain Reaction

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

Magmatic Galleon

When Magmatic Galleon enters, it deals 5 damage to target creature an opponent controls.
Whenever one or more creatures your opponents control are dealt excess noncombat damage, create a Treasure token.
Crew 2

Unquenchable Fury

Enchant creature
Enchanted creature has "Whenever this creature attacks, it deals X damage to defending player, where X is the number of cards in their hand."
When Unquenchable Fury is put into your graveyard from the battlefield, return it to your hand.

Mountain

Crush the Weak

Crush the Weak deals 2 damage to each creature. If a creature dealt damage this way would die this turn, exile it instead.
Foretell {R} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

The Elder Dragon War

Read ahead (Choose a chapter and start with that many lore counters. Add one after your draw step. Skipped chapters don't trigger. Sacrifice after III.)
I — The Elder Dragon War deals 2 damage to each creature and each opponent.
II — Discard any number of cards, then draw that many cards.
III — Create a 4/4 red Dragon creature token with flying.

Mogg Maniac

Whenever Mogg Maniac is dealt damage, it deals that much damage to target opponent or planeswalker.

Decanter of Endless Water

You have no maximum hand size.
{T}: Add one mana of any color.

Pyromania

{1}{R}, Discard a card at random: Pyromania deals 1 damage to any target.
{1}{R}, Sacrifice Pyromania: It deals 1 damage to any target.

Tibalt, the Fiend-Blooded

+1: Draw a card, then discard a card at random.
−4: Tibalt, the Fiend-Blooded deals damage equal to the number of cards in target player's hand to that player.
−6: Gain control of all creatures until end of turn. Untap them. They gain haste until end of turn.

Repercussion

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

Breath Weapon

Breath Weapon deals 2 damage to each non-Dragon creature.

Goldvein Pick

Equipped creature gets +1/+1.
Whenever equipped creature deals combat damage to a player, create a Treasure token. (It's an artifact with "{T}, Sacrifice this token: Add one mana of any color.")
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)