Mikaeus, the Unhallowed + Spawning Pit + Flitterwing Nuisance

Mikaeus, the Unhallowed

Spawning Pit

Flitterwing Nuisance

How it works

1. Activate Spawning Pit by sacrificing Flitterwing Nuisance.
2. When Flitterwing Nuisance dies, its undying ability triggers, returning it from your graveyard to the battlefield without a +1/+1 counter on it due to its replacement effect.
3. Resolve the Spawning Pit ability
4. Repeat.