Grenzo, Dungeon Warden, The Cauldron of Eternity, Ashnod's Altar, and Footlight Fiend

Prerequisites

• All permanents on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Footlight Fiend, adding
2. Footlight Fiend dies, triggering The Caludron of Eternity and itself
3. Resolve The Cauldron of Eternity's trigger, putting Footlight Fiend on the bottom of your library from your graveyard
4. Resolve the Footlight Fiend's trigger, dealing 1 damage to any target
5. Activate Grenzo by paying , putting Footlight Fiendin your graveyard from the bottom of your library, then putting Footlight Fiend onto the battlefield
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite death triggers
• Infinite damage