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.

Reckless One

Haste
Reckless One's power and toughness are each equal to the number of Goblins on the battlefield.

Frenzied Goblin

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

Goblin King

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

Rise of the Hobgoblins

When Rise of the Hobgoblins enters, you may pay {X}. If you do, create X 1/1 red and white Goblin Soldier creature tokens.
{R/W}: Red creatures and white creatures you control gain first strike until end of turn.

Hearthfire Hobgoblin

Goblin Assault Team

Haste
When Goblin Assault Team dies, put a +1/+1 counter on target creature you control.

Krenko, Mob Boss

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

Hobgoblin Bandit Lord

Other Goblins you control get +1/+1.
{R}, {T}: Hobgoblin Bandit Lord deals damage equal to the number of Goblins that entered the battlefield under your control this turn to any target.