Breath of Fury, and Helm of the Host

Prerequisites

• Breath of Fury on the battlefield
• Helm of the Host on the battlefield
• Breath of Fury attached to any other creature you control that can attack this turn and that cannot be blocked by an opponent
• Helm of the Host attached to any creature except the creature that has Breath of Fury attached

Steps

1. At the beginning of your combat phase, Helm of the Host triggers, creating a nonlegendary token copy of the creature it is attached to with haste
2. Deal combat damage to an opponent using the creature that has Breath of Fury attached
3. Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the token created in step 1, 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 combat damage
• Infinite combat phases
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of creatures you control