Hagi Mob

Boast — {1}{R}: Hagi Mob deals 1 damage to any target. (Activate only if this creature attacked this turn and only once each turn.)

Arni Brokenbrow

Haste
Boast — {1}: You may change Arni Brokenbrow's base power to 1 plus the greatest power among other creatures you control until end of turn. (Activate only if this creature attacked this turn and only once each turn.)

Bloodcrazed Goblin

Bloodcrazed Goblin can't attack unless an opponent has been dealt damage this turn.

Goblin Balloon Brigade

{R}: Goblin Balloon Brigade gains flying until end of turn.

Lovisa Coldeyes

Each creature that's a Barbarian, a Warrior, or a Berserker gets +2/+2 and has haste.

Fearless Liberator

Boast — {2}{R}: Create a 2/1 red Dwarf Berserker creature token. (Activate only if this creature attacked this turn and only once each turn.)

Goblin Fireslinger

{T}: Goblin Fireslinger deals 1 damage to target player or planeswalker.

Tuskeri Firewalker

Boast — {1}: Exile the top card of your library. You may play that card this turn. (Activate only if this creature attacked this turn and only once each turn.)

Dragonkin Berserker

First strike
Boast abilities you activate cost {1} less to activate for each Dragon you control.
Boast — {4}{R}: Create a 5/5 red Dragon creature token with flying. (Activate only if this creature attacked this turn and only once each turn.)

Frenzied Raider

Whenever you activate a boast ability, put a +1/+1 counter on Frenzied Raider.

Harnfel, Horn of Bounty

Discard a card: Exile the top two cards of your library. You may play those cards this turn.

Birgi, God of Storytelling

Whenever you cast a spell, add {R}. Until end of turn, you don't lose this mana as steps and phases end.
Creatures you control can boast twice during each of your turns rather than once.

Birgi, God of Storytelling // Harnfel, Horn of Bounty

Frenzied Goblin

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

Rograkh, Son of Rohgahh

First strike, menace, trample
Partner (You can have two commanders if both have partner.)

Goblin Glory Chaser

Renown 1 (When this creature deals combat damage to a player, if it isn't renowned, put a +1/+1 counter on it and it becomes renowned.)
As long as Goblin Glory Chaser is renowned, it has menace. (It can't be blocked except by two or more creatures.)