Mikaeus, the Unhallowed, Soulstinger, and Bloodthrone Vampire

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Soulstinger on the battlefield
• Bloodthrone Vampire on the battlefield

Steps

1. Activate Bloodthrone Vampire by sacrificing Soulstinger
2. When Soulstinger dies, its undying ability and second ability trigger
3. Resolve the second trigger, optionally putting -1/-1 counter(s) on another creature
4. Resolve the Soulstinger trigger, returning it from your graveyard to the battlefield with a +1/+1 counter on it
5. When Soulstinger enters the battlefield, its first ability triggers, putting a -1/-1 counter on it
6. Resolve the Bloodthrone Vampire ability Repeat

Results

• Infinite -1/-1 counters
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite death triggers
• Infinitely large creature until end of turn