Wasitora and Breath of Fury on the battlefield (Breath of Fury attached to any other creature except Wasitora).
An opponent controls no creatures.
You control at least one Mountain.
Steps
Deal combat damage to an opponent who controls no creatures using Wasitora and the creature that has Breath of Fury attached, triggering Breath of Fury and Wasitora.
Resolve the Wasitora trigger, creating a 3/3 Cat Dragon creature token.
Resolve the Breath of Fury trigger, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the Cat Dragon, then causing you to untap all creatures and to get an additional combat phase after this one.