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}.

Fight with Fire

Kicker {5}{R} (You may pay an additional {5}{R} as you cast this spell.)
Fight with Fire deals 5 damage to target creature. If this spell was kicked, it deals 10 damage divided as you choose among any number of targets instead. (Those targets can include players and planeswalkers.)

Demonic Ruckus

Enchant creature
Enchanted creature gets +1/+1 and has menace and trample.
When this Aura is put into a graveyard from the battlefield, draw a card.
Plot {R} (You may pay {R} and exile this card from your hand. Cast it as a sorcery on a later turn without paying its mana cost. Plot only as a sorcery.)

Molten Man, Inferno Incarnate

When Molten Man enters, search your library for a basic Mountain card, put it onto the battlefield tapped, then shuffle.
Molten Man gets +1/+1 for each Mountain you control.
When Molten Man leaves the battlefield, sacrifice a land.

Clamorous Ironclad

Menace (This creature can't be blocked except by two or more creatures.)
Crew 3 (Tap any number of creatures you control with total power 3 or more: This Vehicle becomes an artifact creature until end of turn.)
Cycling {R} ({R}, Discard this card: Draw a card.)

Overwhelming Surge

Choose one or both —
• Overwhelming Surge deals 3 damage to target creature.
• Destroy target noncreature artifact.

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.

Stormblood Berserker

Bloodthirst 2 (If an opponent was dealt damage this turn, this creature enters with two +1/+1 counters on it.)
Menace (This creature can't be blocked except by two or more creatures.)

Frilled Sparkshooter

Menace, reach
This creature enters with a +1/+1 counter on it if an opponent lost life this turn.

Stegron the Dinosaur Man

Menace (This creature can't be blocked except by two or more creatures.)
Dinosaur Formula — {1}{R}, Discard this card: Until end of turn, target creature you control gets +3/+1 and becomes a Dinosaur in addition to its other types.

Ghor-Clan Wrecker

Riot (This creature enters with your choice of a +1/+1 counter or haste.)
Menace (This creature can't be blocked except by two or more creatures.)

Volcanic Geyser

Volcanic Geyser deals X damage to any target.

Superior Foes of Spider-Man

Trample
Whenever you cast a spell with mana value 4 or greater, you may exile the top card of your library. If you do, you may play that card until you exile another card with this creature.

Price of Progress

Price of Progress deals damage to each player equal to twice the number of nonbasic lands that player controls.

Shock Brigade

Menace (This creature can't be blocked except by two or more creatures.)
Mobilize 1 (Whenever this creature attacks, create a tapped and attacking 1/1 red Warrior creature token. Sacrifice it at the beginning of the next end step.)

Mountain

Embercleave

Flash
This spell costs {1} less to cast for each attacking creature you control.
When Embercleave enters, attach it to target creature you control.
Equipped creature gets +1/+1 and has double strike and trample.
Equip {3}

Ruby Medallion

Red spells you cast cost {1} less to cast.

Valley Rally

Gift a Food (You may promise an opponent a gift as you cast this spell. If you do, they create a Food token before its other effects. It's an artifact with "{2}, {T}, Sacrifice this token: You gain 3 life.")
Creatures you control get +2/+0 until end of turn. If the gift was promised, target creature you control gains first strike until end of turn.

Blasphemous Act

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

Mind's Eye

Whenever an opponent draws a card, you may pay {1}. If you do, draw a card.

Ripscale Predator

Menace (This creature can't be blocked except by two or more creatures.)

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.

Bedhead Beastie

Menace (This creature can't be blocked except by two or more creatures.)
Mountaincycling {2} ({2}, Discard this card: Search your library for a Mountain card, reveal it, put it into your hand, then shuffle.)

Goblin Trailblazer

Heroes' Hangout

Choose one —
• Date Night — Exile the top two cards of your library. Choose one of them. Until the end of your next turn, you may play that card.
• Patrol Night — One or two target creatures each get +1/+0 and gain first strike until end of turn.

Drill Too Deep

Choose one —
• Put five charge counters on target Spacecraft or Planet you control.
• Destroy target artifact.

Dragon's Claw

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

Dragon Mantle

Enchant creature
When this Aura enters, draw a card.
Enchanted creature has "{R}: This creature gets +1/+0 until end of turn."

Romantic Rendezvous

Rohirrim Lancer

Menace (This creature can't be blocked except by two or more creatures.)
When this creature dies, the Ring tempts you.

Slaying Fire

Slaying Fire deals 3 damage to any target.
Adamant — If at least three red mana was spent to cast this spell, it deals 4 damage instead.

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.

Kavaron Turbodrone

{T}: Target creature you control gets +1/+1 and gains haste until end of turn. Activate only as a sorcery.

Haste Magic

Target creature gets +3/+1 and gains haste until end of turn. Exile the top card of your library. You may play it until your next end step.

Meteoric Mace

Equipped creature gets +4/+0 and has trample.
Equip {4}
Cascade (When you cast this spell, exile cards from the top of your library until you exile a nonland card that costs less. You may cast it without paying its mana cost. Put the exiled cards on the bottom in a random order.)

Outlaws' Fury

Creatures you control get +2/+0 until end of turn. If you control an outlaw, exile the top card of your library. Until the end of your next turn, you may play that card. (Assassins, Mercenaries, Pirates, Rogues, and Warlocks are outlaws.)

Endrider Catalyzer

Start your engines! (If you have no speed, it starts at 1. It increases once on each of your turns when an opponent loses life. Max speed is 4.)
Max speed — {T}: Add {R}{R}.

Dinotomaton

Menace (This creature can't be blocked except by two or more creatures.)
When this creature enters, target creature you control gains menace until end of turn.

Byway Barterer

Menace
Whenever you expend 4, you may discard your hand. If you do, draw two cards. (You expend 4 as you spend your fourth total mana to cast spells during a turn.)

J. Jonah Jameson

When J. Jonah Jameson enters, suspect up to one target creature. (A suspected creature has menace and can't block.)
Whenever a creature you control with menace attacks, create a Treasure token.

Smash to Dust

Choose one —
• Destroy target artifact.
• Destroy target creature with defender.
• Smash to Dust deals 1 damage to each creature your opponents control.

Wisecrack

Target creature deals damage equal to its power to itself. If that creature is attacking, Wisecrack deals 2 damage to that creature's controller.