Celestial Mantle, and Defiling Daemogoth

Prerequisites

• Celestial Mantle on the battlefield
• Defiling Daemogoth on the battlefield

Steps

1. Deal combat damage using the creature with Celestial Mantle attached, triggering Celestial Mantle, doubling your life total
2. At the beginning of your end step, Defiling Daemogoth triggers, causing each opponent to lose life equal to the life you've lost this turn

Results

• Near-infinite lifeloss
• Near-infinite lifegain