Spawning Pit + Fiend Hunter + Sun Titan

Spawning Pit

Fiend Hunter

Sun Titan

How it works

1. Cast Fiend Hunter by paying its mana cost.
2. When Fiend Hunter enters, its first ability triggers, exiling Sun Titan.
3. Activate Spawning Pit by sacrificing Fiend Hunter.
4. When Fiend Hunter dies, its second ability triggers, returning Sun Titan from exile to the battlefield.
5. When Sun Titan enters, it triggers, returning Fiend Hunter from your graveyard to the battlefield.
6. When Fiend Hunter enters, its first ability triggers, exiling Sun Titan.
7. Resolve the Spawning Pit ability.
8. Repeat from step 3.