Sigarda's Summons, Bishop of Wings, Cathars' Crusade, and Altar of Dementia

Prerequisites

• Sigarda's Summons on the battlefield
• Bishop of Wings on the battlefield
• Cathars' Crusade on the battlefield
• Altar of Dementia on the battlefield
• You control an additional Angel

Steps

1. Activate Altar of Dementia by sacrificing an Angel
2. Bishop of Wings triggers, creating a 1/1 Spirit creature token
3. The Spirit enters the battlefield, triggering Cathars' Crusade, putting a +1/+1 counter on each creature you control
4. The Spirit token becomes a 4/4 Spirit Angel due to having a +1/+1 counter on it
5. Resolve Altar of Dementia's ability, causing target player to mill cards equal to the Angel's power
6. Activate Altar of Dementia by sacrificing the Spirit token
7. Repeat from step 2

Results

• Infinite +1/+1 counters
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill