Goblin Matron

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

Goblin Rabblemaster

Other Goblin creatures you control attack each combat if able.
At the beginning of combat on your turn, create a 1/1 red Goblin creature token with haste.
Whenever Goblin Rabblemaster attacks, it gets +1/+0 until end of turn for each other attacking Goblin.

Raging Goblin

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

Goblin War Drums

Creatures you control have menace. (They can't be blocked except by two or more creatures.)

Krenko, Tin Street Kingpin

Whenever Krenko, Tin Street Kingpin attacks, put a +1/+1 counter on it, then create a number of 1/1 red Goblin creature tokens equal to Krenko's power.

Goblin King

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

Goblin Warchief

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