Underworld Breach, Snubhorn Sentry, Altar of Dementia, and Pitiless Plunderer

Prerequisites

• Underworld Breach on the battlefield
• Snubhorn Sentry on the battlefield
• Altar of Dementia on the battlefield
• Pitiless Plunderer on the battlefield
• You have the city's blessing

Steps

1. Activate Altar of Dementia by sacrificing Snubhorn Sentry
2. When Snubhorn Sentry dies, Pitiless Plunderer triggers, creating a Treasure artifact token
3. Resolve the Altar of Dementia ability, causing you to mill cards equal to Snubhorn Sentry's power
4. Activate the Treasure by tapping and sacrificing it, adding
5. Cast Snubhorn Sentry from your graveyard by paying plus exiling three other cards from your graveyard
6. Repeat

Results

• Infinite self-mill
• Near-infinite death triggers
• Near-infinite ETB
• Near-infinite LTB
• Near-infinite sacrifice triggers
• Near-infinite storm count