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.

Krenko, Mob Boss

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

Goblin Warchief

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

Den of the Bugbear

If you control two or more other lands, this land enters tapped.
{T}: Add {R}.
{3}{R}: Until end of turn, this land becomes a 3/2 red Goblin creature with "Whenever this creature attacks, create a 1/1 red Goblin creature token that's tapped and attacking." It's still a land.

Goblin Bombardment

Sacrifice a creature: This enchantment deals 1 damage to any target.

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.

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.

Krenko, Tin Street Kingpin

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

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Goblin Gathering

Create a number of 1/1 red Goblin creature tokens equal to two plus the number of cards named Goblin Gathering in your graveyard.

Mountain

Skirk Prospector

Goblin King

Other Goblins get +1/+1 and have mountainwalk.

Goblin Trashmaster

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

Pashalik Mons

Whenever Pashalik Mons or another Goblin you control dies, Pashalik Mons deals 1 damage to any target.
{3}{R}, Sacrifice a Goblin: Create two 1/1 red Goblin creature tokens.