Valkyrie's Call + Amoeboid Changeling + Spawning Pit + Glamermite

Valkyrie's Call

Amoeboid Changeling

Spawning Pit

Glamermite

How it works

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