Mikaeus, the Unhallowed, Soulstinger, and Yahenni, Undying Partisan

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Soulstinger on the battlefield
• Yahenni, Undying Partisan on the battlefield

Steps

1. Activate Yahenni by sacrificing Soulstinger
2. When Soulstinger dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When Soulstinger enters the battlefield, it triggers, putting a -1/-1 counter on it
4. Resolve the Yahenni ability Repeat

Results

• Infinite -1/-1 counters
• Infinite death triggers
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers