Mikaeus, the Unhallowed, Spawning Pit, and Morselhoarder

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Spawning Pit on the battlefield
• Morselhoarder on the battlefield

Steps

1. Activate Spawning Pit by sacrificing Morselhoarder
2. When Morselhoarder dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect
3. Resolve the Spawning Pit ability Activate Morselhoarder by removing a -1/-1 counter from it, adding one mana of any color Repeat

Results

• Infinite artifact ETB
• Infinite artifact LTB
• Infinite artifact sacrifice triggers
• Infinite artifact tokens
• Infinite charge counters on a permanent
• Infinite colored mana
• Infinite creature ETB
• Infinite creature LTB
• Infinite creature sacrifice triggers
• Infinite creature tokens
• Infinite death triggers