Breath of Fury, and Urabrask's Forge

Prerequisites

• Breath of Fury on the battlefield
• Urabrask's Forge on the battlefield

Steps

1. At the beginning of your combat phase, Urabrask's Forge triggers, creating a creature token
2. Deal combat damage 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 creature 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 mana creatures you control can produce
• Infinite sacrifice triggers
• Infinite untap of creatures you control
• Infinite combat damage
• Infinite combat phases
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinitely powerful creature until end of turn