Breath of Fury attached to another creature you control that can attack this turn.
Your commander is on the battlefield and is a creature.
Opponents cannot block creatures you control.
Your commander does not have summoning sickness.
Steps
Declare the creature with Breath of Fury attached and your commander as attackers, attacking the opponent with the highest life total among your opponents or an opponent that is tied for the highest life total among your opponents.
Your commander triggers, creating two 2/2 Cat creature tokens with haste due to Jinnie Fay.
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 Cat token, then causing you to untap all creatures you control and to get an additional combat phase after this one.
Repeat each combat phase.
Once you have infinite Cat tokens, you may instead make Dog tokens using Jinnie Fay or Treasure tokens.