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 Piledriver

Protection from blue (This creature can't be blocked, targeted, dealt damage, or enchanted by anything blue.)
Whenever Goblin Piledriver attacks, it gets +2/+0 until end of turn for each other attacking Goblin.

Goblin King

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

Goblin Bombardment

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

Krenko's Command

Create two 1/1 red Goblin creature tokens.

Krenko, Mob Boss

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

Gamble

Search your library for a card, put that card into your hand, discard a card at random, then shuffle.