Goblin Piledriver

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

Sparksmith

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

Brightstone Ritual

Add {R} for each Goblin on the battlefield.

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Goblin Matron

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

Gempalm Incinerator

Cycling {1}{R} ({1}{R}, Discard this card: Draw a card.)
When you cycle this card, you may have it deal X damage to target creature, where X is the number of Goblins on the battlefield.

Skirk Fire Marshal

Protection from red
Tap five untapped Goblins you control: This creature deals 10 damage to each creature and each player.

Skirk Prospector

Mogg Maniac

Whenever this creature is dealt damage, it deals that much damage to target opponent or planeswalker.

Mountain

Goblin Lackey

Whenever this creature deals damage to a player, you may put a Goblin permanent card from your hand onto the battlefield.

Siege-Gang Commander

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