Mikaeus, the Unhallowed, Pith Driller, and Ravenous Intruder

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Pith Driller on the battlefield
• Ravenous Intruder on the battlefield
• Pith Driller does not have a +1/+1 counter on it

Steps

1. Activate Ravenous Intruder by sacrifiicing Pith Driller
2. When Pith Driller dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When Pith Driller enters the battlefield, it triggers, putting a -1/-1 counter on it
4. Resolve the Ravenous Intruder ability
5. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinitely large Ravenous Intruder until end of turn