Goblin Warchief

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

Krenko, Mob Boss

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

Whenever this creature attacks, you may pay {R}. If you do, target creature can't block this turn.

Create four 1/1 red Goblin creature tokens.

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