Breath of Fury attached to any other creature you control that does not have summoning sickness.
You control any number of creatures with power 6 or greater including Battle Cry Goblin that do not have summoning sickness.
An opponent cannot block creatures you control.
Steps
Declare Battle Cry Goblin, the creature with Breath of Fury attached, and any number of other creatures as attackers.
Battle Cry Goblin triggers, creating a 1/1 Goblin creature token that is tapped and attacking.
Deal combat damage using the creature that has Breath of Fury attached.
Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Goblin token, then causing you to untap all creatures you control and to get an additional combat phase after this one.