Blazing Sunsteel, and Phyrexian Metamorph

Prerequisites

• Blazing Sunsteel on the battlefield
• Phyrexian Metamorph on the battlefield
• Blazing Sunsteel and Phyrexian Metamorph attached to an indestructible creature you control
• You have a way to deal damage to the indestructible creature

Steps

1. Deal damage to the indestructible creature
2. Blazing Sunsteel and Phyrexian Metamorph trigger
3. Resolve the Blazing Sunsteel trigger, dealing damage equal to the damage dealt to any target
4. Resolve the Phyrexian Metamorph trigger, dealing damage equal to the damage dealt to the indestructible creature
5. Repeat from step 2

Results

• Infinite damage