Have

Mountain

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Foundry Street Denizen

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

Electrickery

Electrickery deals 1 damage to target creature you don't control.
Overload {1}{R} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Intimidator Initiate

Whenever a player casts a red spell, you may pay {1}. If you do, target creature can't block this turn.

Mogg Conscripts

Mogg Conscripts can't attack unless you've cast a creature spell this turn.

Flame Slash

Flame Slash deals 4 damage to target creature.

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.

Goblin Cohort

Goblin Cohort can't attack unless you've cast a creature spell this turn.

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.

Tarfire

Flaring Pain

Damage can't be prevented this turn.
Flashback {R} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Sparksmith

{T}: Sparksmith deals X damage to target creature and X damage to you, where X is the number of Goblins on the battlefield.

Goblin Sledder

Sacrifice a Goblin: Target creature gets +1/+1 until end of turn.

Smash to Smithereens

Destroy target artifact. Smash to Smithereens deals 3 damage to that artifact's controller.

Fireblast

You may sacrifice two Mountains rather than pay this spell's mana cost.
Fireblast deals 4 damage to any target.

Raze

As an additional cost to cast this spell, sacrifice a land.
Destroy target land.

Goblin Heelcutter

Whenever Goblin Heelcutter attacks, target creature can't block this turn.
Dash {2}{R} (You may cast this spell for its dash cost. If you do, it gains haste, and it's returned from the battlefield to its owner's hand at the beginning of the next end step.)

Goblin Bushwhacker

Kicker {R} (You may pay an additional {R} as you cast this spell.)
When this creature enters, if it was kicked, creatures you control get +1/+0 and gain haste until end of turn.