Goblin King

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

Krenko, Mob Boss

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

Swamp

Mountain

Murder

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

Return

Aftermath (Cast this spell only from your graveyard. Then exile it.)
Exile target card from a graveyard. Create a 2/2 black Zombie creature token.

Never

Never // Return

Hero's Downfall

Goblin Arsonist

When this creature dies, you may have it deal 1 damage to any target.

Infernal Reckoning

Exile target colorless creature. You gain life equal to its power.

Aligned Hedron Network

When this artifact enters, exile all creatures with power 5 or greater until this artifact leaves the battlefield. (Those creatures return under their owners' control.)

Legion Loyalist

Haste
Battalion — Whenever this creature and at least two other creatures attack, creatures you control gain first strike and trample until end of turn and can't be blocked by creature tokens this turn.

Goblin Wizard

{T}: You may put a Goblin permanent card from your hand onto the battlefield.
{R}: Target Goblin gains protection from white until end of turn.