Mortuary, Bolas's Citadel, Umbral Collar Zealot, and Serrated Scorpion

Prerequisites

• Mortuary on the battlefield
• Bolas's Citadel on the battlefield
• Umbral Collar Zealot on the battlefield
• Serrated Scorpion in hand

Steps

1. Activate Umbral Collar Zealot by sacrificing Serrated Scorpion
2. When Serrated Scorpion dies, it and Mortuary triggers
3. Resolve the Mortuary trigger, putting Serrated Scorpion from your graveyard onto the top of your library
4. Resolve the Serrated Scorpion trigger, causing you to gain 2 life and dealing 2 damage to each opponent
5. Resolve the Umbral Collar Zealot ability
6. Cast Serrated Scorpion from the top of your library by paying 1 life due to Bolas's Citadel
7. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite lifegain
• Infinite storm count
• Infinite surveil 1
• Infinite damage