Valkyrie's Call, Amoeboid Changeling, Spawning Pit, and Hyrax Tower Scout

Prerequisites

• Valkyrie's Call on the battlefield
• Amoeboid Changeling on the battlefield
• Spawning Pit on the battlefield
• Hyrax Tower Scout on the battlefield

Steps

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