Release the Gremlins

Destroy X target artifacts. Create X 2/2 red Gremlin creature tokens.

Tuktuk the Explorer

Haste
When Tuktuk the Explorer dies, create Tuktuk the Returned, a legendary 5/5 colorless Goblin Golem artifact creature token.

Grinning Ignus

{R}, Return Grinning Ignus to its owner's hand: Add {C}{C}{R}. Activate only as a sorcery.

Ruby Medallion

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

Young Pyromancer

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

Thopter Engineer

When Thopter Engineer enters, create a 1/1 colorless Thopter artifact creature token with flying.
Artifact creatures you control have haste. (They can attack and {T} as soon as they come under your control.)

Dance with Devils

Create two 1/1 red Devil creature tokens. They have "When this creature dies, it deals 1 damage to any target."

Krenko, Mob Boss

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

Goblin Assault

At the beginning of your upkeep, create a 1/1 red Goblin creature token with haste.
Goblin creatures attack each combat if able.

Goblin Trashmaster

Other Goblins you control get +1/+1.
Sacrifice a Goblin: Destroy target artifact.

Emrakul's Hatcher

When Emrakul's Hatcher enters, create three 0/1 colorless Eldrazi Spawn creature tokens. They have "Sacrifice this creature: Add {C}."

Temple of the False God

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

Impact Tremors

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

Guttersnipe

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

Chandra's Spitfire

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

Goblin Marshal

Echo {4}{R}{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 Goblin Marshal enters or dies, create two 1/1 red Goblin creature tokens.

Hordeling Outburst

Create three 1/1 red Goblin creature tokens.

Chancellor of the Forge

You may reveal this card from your opening hand. If you do, at the beginning of the first upkeep, create a 1/1 red Phyrexian Goblin creature token with haste.
When Chancellor of the Forge enters, create X 1/1 red Phyrexian Goblin creature tokens with haste, where X is the number of creatures you control.

Pia Nalaar

When Pia Nalaar enters, create a 1/1 colorless Thopter artifact creature token with flying.
{1}{R}: Target artifact creature gets +1/+0 until end of turn.
{1}, Sacrifice an artifact: Target creature can't block this turn.

Firecat Blitz

Create X 1/1 red Elemental Cat creature tokens with haste. Exile them at the beginning of the next end step.
Flashback—{R}{R}, Sacrifice X Mountains. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

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.

Mountain

Mogg Alarm

You may sacrifice two Mountains rather than pay this spell's mana cost.
Create two 1/1 red Goblin creature tokens.

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.

Mob Justice

Mob Justice deals damage to target player or planeswalker equal to the number of creatures you control.

Rakka Mar

Haste
{R}, {T}: Create a 3/1 red Elemental creature token with haste.

Kari Zev, Skyship Raider

First strike, menace
Whenever Kari Zev, Skyship Raider attacks, create Ragavan, a legendary 2/1 red Monkey creature token. Ragavan enters tapped and attacking. Exile that token at end of combat.

Goblin Instigator

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

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.

Tooth and Claw

Sacrifice two creatures: Create a 3/1 red Beast creature token named Carnivore.

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.

Paragon of Fierce Defiance

Other red creatures you control get +1/+1.
{R}, {T}: Another target red creature you control gains haste until end of turn. (It can attack and {T} this turn.)

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}.

Throne of the God-Pharaoh

At the beginning of your end step, each opponent loses life equal to the number of tapped creatures you control.

Fanatic of Mogis

When Fanatic of Mogis enters, it deals damage to each opponent equal to your devotion to red. (Each {R} in the mana costs of permanents you control counts toward your devotion to red.)

Shock

Empty the Warrens

Create two 1/1 red Goblin creature tokens.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Beetleback Chief

When Beetleback Chief enters, create two 1/1 red Goblin creature tokens.

Dragon Fodder

Create two 1/1 red Goblin creature tokens.

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.

Panharmonicon

If an artifact or creature entering causes a triggered ability of a permanent you control to trigger, that ability triggers an additional time.

Wily Goblin

When Wily Goblin enters, create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Pia and Kiran Nalaar

When Pia and Kiran Nalaar enters, create two 1/1 colorless Thopter artifact creature tokens with flying.
{2}{R}, Sacrifice an artifact: Pia and Kiran Nalaar deals 2 damage to any target.

Descent of the Dragons

Destroy any number of target creatures. For each creature destroyed this way, its controller creates a 4/4 red Dragon creature token with flying.

Foundry Street Denizen

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

Vandalblast

Destroy target artifact you don't control.
Overload {4}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Hellion Eruption

Sacrifice all creatures you control, then create that many 4/4 red Hellion creature tokens.

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.

Hammer of Purphoros

Creatures you control have haste.
{2}{R}, {T}, Sacrifice a land: Create a 3/3 colorless Golem enchantment artifact creature token.

Thatcher Revolt

Create three 1/1 red Human creature tokens with haste. Sacrifice those tokens at the beginning of the next end step.

Tilonalli's Summoner

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
Whenever Tilonalli's Summoner attacks, you may pay {X}{R}. If you do, create X 1/1 red Elemental creature tokens that are tapped and attacking. At the beginning of the next end step, exile those tokens unless you have the city's blessing.

Battle Hymn

Goblin Scouts

Create three 1/1 red Goblin Scout creature tokens with mountainwalk. (They can't be blocked as long as defending player controls a Mountain.)

Kuldotha Rebirth

As an additional cost to cast this spell, sacrifice an artifact.
Create three 1/1 red Goblin creature tokens.

Flurry of Horns

Create two 2/3 red Minotaur creature tokens with haste.

Krenko's Command

Goblinslide

Whenever you cast a noncreature spell, you may pay {1}. If you do, create a 1/1 red Goblin creature token with haste.

Mana Geyser

Add {R} for each tapped land your opponents control.

Goblin Rally

Create four 1/1 red Goblin creature tokens.

Massive Raid

Massive Raid deals damage to any target equal to the number of creatures you control.

Devils' Playground

Create four 1/1 red Devil creature tokens. They have "When this creature dies, it deals 1 damage to any target."

Goblin Warrens

{2}{R}, Sacrifice two Goblins: Create three 1/1 red Goblin creature tokens.

Ib Halfheart, Goblin Tactician

Whenever another Goblin you control becomes blocked, sacrifice it. If you do, it deals 4 damage to each creature blocking it.
Sacrifice two Mountains: Create two 1/1 red Goblin creature tokens.

Mogg War Marshal

Echo {1}{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 Mogg War Marshal enters or dies, create a 1/1 red Goblin creature token.

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.

Rummaging Goblin

Lightning Strike

Lightning Strike deals 3 damage to any target.

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.")

Goblin Warchief

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

Molten Birth

Create two 1/1 red Elemental creature tokens, then flip a coin. If you win the flip, return Molten Birth to its owner's hand.

Goblin Offensive

Goblin Wardriver

Battle cry (Whenever this creature attacks, each other attacking creature gets +1/+0 until end of turn.)