Valkyrie's Call, Amoeboid Changeling, Spawning Pit, and Derevi, Empyrial Tactician

Prerequisites

• Valkyrie's Call on the battlefield
• Amoeboid Changeling on the battlefield
• Spawning Pit on the battlefield
• Derevi, Empyrial Tactician on the battlefield

Steps

1. Activate Amoeboid Changeling's second ability by tapping it, removing all creature types from Derevi
2. Activate Spawning Pit by sacrificing Derevi
3. When Derevi dies, Valkyrie's Call triggers, returning Derevi from your graveyard to the battlefield as an Angel with flying and a +1/+1 counter on it
4. When Derevi 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 sacrifice triggers
• Infinite death triggers
• Infinite charge counters on a permanent