Sidisi, Regent of the Mire, Sister Hospitaller, Grimgrin, Corpse-Born, and Sky Hussar

Prerequisites

• Sidisi, Regent of the Mire on the battlefield
• Sister Hospitaller in the graveyard
• Grimgrin, Corpse-Born on the battlefield
• Sky Hussar on the battlefield

Steps

1. Activate Sidisi by tapping it and sacrificing Sky Hussar, returning Sister Hospitaller from your graveyard to the battlefield
2. When Sister Hospitaller enters the battlefield, it triggers, returning Sky Hussar from your graveyard to the battlefield and causing you to gain 5 life
3. When Sky Hussar enters the battlefield, it triggers, untapping Sidisi
4. Activate Grimgrin by sacrificing Sister Hospitaller
5. Repeat

Results

• Infinite +1/+1 counters on a creature
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinite lifegain
• Infinite lifegain triggers
• Infinite mana creatures you control can produce
• Infinite untap of creatures you control