Prototype Portal, Dross Scorpion, Altar of Dementia, and Su-Chi

Prerequisites

• Prototype Portal on the battlefield
• Dross Scorpion on the battlefield
• Altar of Dementia on the battlefield
• Su-Chi on the battlefield
• undefined available

Steps

1. Activate Prototype Portal by paying and tapping it, creating a token copy of Su-Chi
2. Activate Altar of Dementia by sacrificing Su-Chi
3. When Su-Chi dies, Su-Chi and Dross Scorpion trigger
4. Resolve the Su-Chi trigger, adding
5. Resolve the Dross Scorpion trigger, untapping Prototype Portal
6. Resolve the Altar of Dementia ability, milling target player a number of cards equal to the sacrificed creature's power
7. Repeat

Results

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