Hobgoblin Bandit Lord

Other Goblins you control get +1/+1.
{R}, {T}: Hobgoblin Bandit Lord deals damage equal to the number of Goblins that entered the battlefield under your control this turn to any target.

Hordeling Outburst

Create three 1/1 red Goblin creature tokens.

Mountain

Brightstone Ritual

Add {R} for each Goblin on the battlefield.

Goblin War Strike

Goblin War Strike deals damage to target player or planeswalker equal to the number of Goblins you control.

Raging Goblin

Haste (This creature can attack and {T} as soon as it comes under your control.)

Hobgoblin Captain

Pack tactics — Whenever Hobgoblin Captain attacks, if you attacked with creatures with total power 6 or greater this combat, Hobgoblin Captain gains first strike until end of turn.

Goblin Balloon Brigade

{R}: Goblin Balloon Brigade gains flying until end of turn.

Dark-Dweller Oracle

{1}, Sacrifice a creature: Exile the top card of your library. You may play that card this turn. (You still pay its costs. You can play a land this way only if you have an available land play remaining.)

Goblin King

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

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's Command

Create two 1/1 red Goblin creature tokens.

Impact Tremors

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

Den of the Bugbear

If you control two or more other lands, Den of the Bugbear enters tapped.
{T}: Add {R}.
{3}{R}: Until end of turn, Den of the Bugbear 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.

Skirk Prospector

Krenko, Mob Boss

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

Battle Cry Goblin

{1}{R}: Goblins you control get +1/+0 and gain haste until end of turn.
Whenever Battle Cry Goblin attacks, if you attacked with creatures with total power 6 or greater this combat, create a 1/1 red Goblin creature token that's tapped and attacking.