Act of Treason

Gain control of target creature until end of turn. Untap that creature. It gains haste until end of turn. (It can attack and {T} this turn.)

Goblin Trashmaster

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

Goblin Motivator

{T}: Target creature gains haste until end of turn. (It can attack and {T} this turn.)

Havoc Devils

Trample (This creature can deal excess combat damage to the player or planeswalker it's attacking.)

Tormenting Voice

As an additional cost to cast this spell, discard a card.
Draw two cards.

Volley Veteran

When this creature enters, it deals damage to target creature an opponent controls equal to the number of Goblins you control.

Goblin Instigator

When Goblin Instigator enters, create a 1/1 red Goblin creature token.

Dragon Fodder

Create two 1/1 red Goblin creature tokens.

Mountain

Captivating Crew

{3}{R}: Gain control of target creature an opponent controls until end of turn. Untap that creature. It gains haste until end of turn. Activate only as a sorcery.

Shivan Dragon

Flying
{R}: This creature gets +1/+0 until end of turn.

Eager Construct

When Eager Construct enters, each player may scry 1. (To scry 1, look at the top card of your library, then you may put that card on the bottom.)

Welder Automaton

{3}{R}: Welder Automaton deals 1 damage to each opponent.

Demanding Dragon

Flying
When Demanding Dragon enters, it deals 5 damage to target opponent unless that player sacrifices a creature of their choice.

Howling Golem

Whenever Howling Golem attacks or blocks, each player draws a card.

Siege-Gang Commander

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

Bombard

Bombard deals 4 damage to target creature.

Trumpet Blast

Attacking creatures get +2/+0 until end of turn.

Rolling Thunder

Rolling Thunder deals X damage divided as you choose among any number of targets.

Seismic Elemental

When Seismic Elemental enters, creatures without flying can't block this turn.

Guttersnipe

Whenever you cast an instant or sorcery spell, this creature deals 2 damage to each opponent.

Shock

Goblin Goliath

When Goblin Goliath enters, create a number of 1/1 red Goblin creature tokens equal to the number of opponents you have.
{3}{R}, {T}: If a source you control would deal damage to an opponent this turn, it deals double that damage to that player instead.