Valkyrie's Call, Amoeboid Changeling, Spawning Pit, and Village Bell-Ringer

Prerequisites

• Valkyrie's Call on the battlefield
• Amoeboid Changeling on the battlefield
• Spawning Pit on the battlefield
• Village Bell-Ringer on the battlefield

Steps

1. Activate Amoeboid Changeling's second ability by tapping it, removing all creature types from Village Bell-Ringer
2. Activate Spawning Pit by sacrificing Village Bell-Ringer
3. When Village Bell-Ringer dies, Valkyrie's Call triggers, returning Village Bell-Ringer from your graveyard to the battlefield as an Angel with flying and a +1/+1 counter on it
4. When Village Bell-Ringer enters the battlefield, it triggers, untapping Amoeboid Changeling
5. Resolve the Spawning Pit ability, putting a charge counter on it
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite untap of creatures you control
• Infinite mana creatures you control can produce
• Infinite charge counters on a permanent
• Infinite sacrifice triggers
• Infinite death triggers