Walking Ballista, and Mikaeus, the Unhallowed

Prerequisites

• Walking Ballista on the battlefield
• Mikaeus, the Unhallowed on the battlefield
• Walking Ballista on the battlefield with a +1/+1 counter on it

Steps

1. Activate Walking Ballista's last ability by removing a +1/+1 counter from it, dealing 1 damage to itself
2. Walking Ballista dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite LTB