Sidisi, Regent of the Mire, Sister Hospitaller, Thornbite Staff, and Yahenni, Undying Partisan

Prerequisites

• Sidisi, Regent of the Mire on the battlefield
• Sister Hospitaller in the graveyard
• Thornbite Staff on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Sidisi by tapping it and sacrificing a nontoken creature with mana value 5
2. When the creature dies, Sidisi triggers, untapping Sidisi
3. Resolve the Sidisi ability, returning Sister Hospitaller from your graveyard to the battlefield
4. When Sister Hospitaller enters the battlefield, it triggers, returning the creature with mana value 5 from your graveyard to the battlefield and causing you to gain 5 life
5. Activate Yahenni by sacrificing Sister Hospitaller
6. When Sister Hospitaller dies, Sidisi triggers, untapping Sidisi
7. Resolve the Yahenni ability
8. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite lifegain triggers
• Infinite lifegain