Impact Tremors

Whenever a creature you control enters, Impact Tremors deals 1 damage to each opponent.

Krenko, Mob Boss

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

Add {R} for each Goblin on the battlefield.

Sacrifice a Goblin: Regenerate target creature.

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

Sacrifice a creature: Goblin Bombardment deals 1 damage to any target.

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

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

{T}: Add one mana of any color in your commander's color identity.

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

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.