Legion Warboss

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
At the beginning of combat on your turn, create a 1/1 red Goblin creature token. That token gains haste until end of turn and attacks this combat if able.

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.)

Siege-Gang Commander

When Siege-Gang Commander enters, create three 1/1 red Goblin creature tokens.
{1}{R}, Sacrifice a Goblin: Siege-Gang Commander deals 2 damage to any target.

Purphoros's Emissary

Bestow {6}{R} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.)
Menace (This creature can't be blocked except by two or more creatures.)
Enchanted creature gets +3/+3 and has menace.

Goblin Rabblemaster

Other Goblin creatures you control attack each combat if able.
At the beginning of combat on your turn, create a 1/1 red Goblin creature token with haste.
Whenever Goblin Rabblemaster attacks, it gets +1/+0 until end of turn for each other attacking Goblin.

Magus of the Moon

Avalanche Riders

Haste
Echo {3}{R} (At the beginning of your upkeep, if this came under your control since the beginning of your last upkeep, sacrifice it unless you pay its echo cost.)
When Avalanche Riders enters, destroy target land.

Madcap Skills

Enchant creature
Enchanted creature gets +3/+0 and has menace.

Impact Tremors

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

Goblin Piledriver

Protection from blue (This creature can't be blocked, targeted, dealt damage, or enchanted by anything blue.)
Whenever Goblin Piledriver attacks, it gets +2/+0 until end of turn for each other attacking Goblin.

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.")

Valakut, the Molten Pinnacle

Valakut, the Molten Pinnacle enters tapped.
Whenever a Mountain you control enters, if you control at least five other Mountains, you may have Valakut, the Molten Pinnacle deal 3 damage to any target.
{T}: Add {R}.

Charmbreaker Devils

At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Whenever you cast an instant or sorcery spell, Charmbreaker Devils gets +4/+0 until end of turn.

Onslaught

Whenever you cast a creature spell, tap target creature.

Frenzied Rage

Enchant creature
Enchanted creature gets +2/+1 and has menace. (It can't be blocked except by two or more creatures.)

Goblin Warchief

Goblin spells you cast cost {1} less to cast.
Goblins you control have haste.

Krenko, Mob Boss

{T}: Create X 1/1 red Goblin creature tokens, where X is the number of Goblins you control.

Krenko, Tin Street Kingpin

Whenever Krenko, Tin Street Kingpin attacks, put a +1/+1 counter on it, then create a number of 1/1 red Goblin creature tokens equal to Krenko's power.

Anax, Hardened in the Forge

Anax's power is equal to your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)
Whenever Anax or another nontoken creature you control dies, create a 1/1 red Satyr creature token with "This creature can't block." If the creature had power 4 or greater, create two of those tokens instead.

Hammerhand

Enchant creature
When Hammerhand enters, target creature can't block this turn.
Enchanted creature gets +1/+1 and has haste.

Sol Ring

Purphoros, God of the Forge

Indestructible
As long as your devotion to red is less than five, Purphoros isn't a creature.
Whenever another creature you control enters, Purphoros deals 2 damage to each opponent.
{2}{R}: Creatures you control get +1/+0 until end of turn.

Rage Reflection

Creatures you control have double strike.

Torch Fiend

{R}, Sacrifice Torch Fiend: Destroy target artifact.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Searing Blaze

Searing Blaze deals 1 damage to target player or planeswalker and 1 damage to target creature that player or that planeswalker's controller controls.
Landfall — If you had a land enter the battlefield under your control this turn, Searing Blaze deals 3 damage to that player or planeswalker and 3 damage to that creature instead.

Goblin Matron

When Goblin Matron enters, you may search your library for a Goblin card, reveal that card, put it into your hand, then shuffle.

Ruby Medallion

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

Goblin Chainwhirler

First strike
When Goblin Chainwhirler enters, it deals 1 damage to each opponent and each creature and planeswalker they control.

Kazuul, Tyrant of the Cliffs

Whenever a creature an opponent controls attacks, if you're the defending player, create a 3/3 red Ogre creature token unless that creature's controller pays {3}.

Dragon Mantle

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

Chain Lightning

Chain Lightning deals 3 damage to any target. Then that player or that permanent's controller may pay {R}{R}. If the player does, they may copy this spell and may choose a new target for that copy.

Goblin Ringleader

Haste (This creature can attack and {T} as soon as it comes under your control.)
When Goblin Ringleader enters, reveal the top four cards of your library. Put all Goblin cards revealed this way into your hand and the rest on the bottom of your library in any order.

Chandra, Fire Artisan

Whenever one or more loyalty counters are removed from Chandra, Fire Artisan, she deals that much damage to target opponent or planeswalker.
+1: Exile the top card of your library. You may play it this turn.
−7: Exile the top seven cards of your library. You may play them this turn.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Keldon Firebombers

When Keldon Firebombers enters, each player sacrifices all lands they control except for three.

Feldon of the Third Path

{2}{R}, {T}: Create a token that's a copy of target creature card in your graveyard, except it's an artifact in addition to its other types. It gains haste. Sacrifice it at the beginning of the next end step.

Reverberate

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

Electropotence

Whenever a creature you control enters, you may pay {2}{R}. If you do, that creature deals damage equal to its power to any target.

Young Pyromancer

Whenever you cast an instant or sorcery spell, create a 1/1 red Elemental creature token.

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.

Curse of Bloodletting

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

Goblin Instigator

When Goblin Instigator enters, create a 1/1 red Goblin creature token.

Chandra's Incinerator

This spell costs {X} less to cast, where X is the total amount of noncombat damage dealt to your opponents this turn.
Trample
Whenever a source you control deals noncombat damage to an opponent, Chandra's Incinerator deals that much damage to target creature or planeswalker that player controls.

Breath of Fury

Enchant creature you control
When enchanted creature deals combat damage to a player, sacrifice it and attach Breath of Fury to a creature you control. If you do, untap all creatures you control and after this phase, there is an additional combat phase.

Outpost Siege

As Outpost Siege enters, choose Khans or Dragons.
• Khans — At the beginning of your upkeep, exile the top card of your library. Until end of turn, you may play that card.
• Dragons — Whenever a creature you control leaves the battlefield, Outpost Siege deals 1 damage to any target.

Blasphemous Act

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

Banefire

Banefire deals X damage to any target.
If X is 5 or more, this spell can't be countered and the damage can't be prevented.

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Terrain Generator

{T}: Add {C}.
{2}, {T}: You may put a basic land card from your hand onto the battlefield tapped.

Fire Diamond

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

Goblin Chieftain

Haste (This creature can attack and {T} as soon as it comes under your control.)
Other Goblin creatures you control get +1/+1 and have haste.

Volcanic Fallout

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

Warstorm Surge

Whenever a creature you control enters, it deals damage equal to its power to any target.

Myriad Landscape

Myriad Landscape enters 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.

Inferno Titan

{R}: Inferno Titan gets +1/+0 until end of turn.
Whenever Inferno Titan enters or attacks, it deals 3 damage divided as you choose among one, two, or three targets.

Raid Bombardment

Whenever a creature you control with power 2 or less attacks, Raid Bombardment deals 1 damage to the player or planeswalker that creature is attacking.

Ashnod's Altar

Buried Ruin

{T}: Add {C}.
{2}, {T}, Sacrifice Buried Ruin: Return target artifact card from your graveyard to your hand.

Shackles of Treachery

Gain control of target creature until end of turn. Untap that creature. Until end of turn, it gains haste and "Whenever this creature deals damage, destroy target Equipment attached to it."

Chandra's Spitfire

Flying
Whenever an opponent is dealt noncombat damage, Chandra's Spitfire gets +3/+0 until end of turn.

Hellrider

Haste
Whenever a creature you control attacks, Hellrider deals 1 damage to the player or planeswalker it's attacking.

Kiki-Jiki, Mirror Breaker

Haste
{T}: Create a token that's a copy of target nonlegendary creature you control, except it has haste. Sacrifice it at the beginning of the next end step.

Molten Primordial

Haste
When Molten Primordial enters, for each opponent, gain control of up to one target creature that player controls until end of turn. Untap those creatures. They gain haste until end of turn.

Mountain

Blood Mist

At the beginning of combat on your turn, target creature you control gains double strike until end of turn.

Mark of Mutiny

Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn. (It can attack and {T} this turn.)