Sigarda's Summons, Bishop of Wings, Master Biomancer, and Altar of Dementia

Prerequisites

• Sigarda's Summons on the battlefield
• Bishop of Wings on the battlefield
• Master Biomancer on the battlefield
• Altar of Dementia on the battlefield

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 with at least two +1/+1 counters and becomes a 4/4 Spirit Angel due to having a +1/+1 counter on it
4. Bishop of Wings triggers, causing you to gain four life
5. Resolve Altar of Dementia's ability, causing target player to mill a number of cards equal to the sacrificed Angel's power
6. Activate Altar of Dementia by sacrificing the Spirit token
7. Repeat from step 2

Results

• Infinite death triggers
• Infinite ETB
• Infinite lifegain
• Infinite lifegain triggers
• Infinite LTB
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill