Oathkeeper, Takeno's Daisho, Altar of Dementia, and Swordsman, Sharp Scoundrel

Prerequisites

• Oathkeeper, Takeno's Daisho on the battlefield
• Altar of Dementia on the battlefield
• Swordsman, Sharp Scoundrel on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing the creature with changeling
2. When that creature dies, Oathkeeper triggers, returning it from your graveyard to the battlefield
3. When that creature enters, Swordsman triggers, allowing you to attach Oathkeeper to that creature
4. Resolve the Altar of Dementia ability
5. Repeat

Results

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