Oathkeeper, Takeno's Daisho, Umbral Collar Zealot, and Swordsman, Sharp Scoundrel

Prerequisites

• Oathkeeper, Takeno's Daisho on the battlefield
• Umbral Collar Zealot on the battlefield
• Swordsman, Sharp Scoundrel on the battlefield

Steps

1. Activate Umbral Collar Zealot 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 Umbral Collar Zealot ability
5. Repeat

Results

• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite surveil