Goblin Chieftain

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.

Goblin Warchief

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

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.

Patchwork Banner

As Patchwork Banner enters, choose a creature type.
Creatures you control of the chosen type get +1/+1.
{T}: Add one mana of any color.

Marvin, Murderous Mimic

Marvin, Murderous Mimic has all activated abilities of creatures you control that don't have the same name as this creature.

Three Tree City

As Three Tree City enters, choose a creature type.
{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to the number of creatures you control of the chosen type.

Krenko, Mob Boss

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