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

Valkyrie's Call

Amoeboid Changeling

Spawning Pit

Derevi, Empyrial Tactician

How it works

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.