Shaun, Father of Synths, and Breath of Fury

Prerequisites

• Shaun, Father of Synths on the battlefield
• Breath of Fury on the battlefield
• An opponent cannot block creatures you control
• Breath of Fury attached to any other creature you control that does not have summoning sickness

Steps

1. Declare the legendary creature with haste and the creature with Breath of Fury attached as attackers
2. Shaun's first ability triggers, creating a tapped and attacking token of the legendary creature with haste that isn't legendary
3. Deal combat damage using the creature that has Breath of Fury attached
4. Breath of Fury triggers, causing you to sacrifice the creature it is attached to, then attach Breath of Fury to the token copy of the legendary creature with haste, then causing you to untap all creatures you control and to get an additional combat phase after this one
5. Repeat each combat phase

Results

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