Primo, the Unbounded, Breath of Fury, and Barbarian Class

Prerequisites

• Primo, the Unbounded on the battlefield
• Breath of Fury on the battlefield
• Barbarian Class on the battlefield

Steps

1. Deal combat damage to an opponent using the creature that has Breath of Fury attached, triggering Breath of Fury and Primo
2. Resolve the Primo trigger, creating a 0/0 Fractal creature token that enters with a number of +1/+1 counters on it equal to the damage dealt
3. Resolve the Breath of Fury trigger, causing you to sacrifice the creature it is attached to and attach it to the Fractal token, then causing you to untap all creatures you control and to get an additional combat phase after this one
4. Repeat each combat phase

Results

• Infinite ETB
• Infinite LTB
• Infinite combat damage
• Infinite combat phases
• Infinite death triggers
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of creatures you control