Radiant Solar + Sefris of the Hidden Ways + Fiend Hunter + Ravenloft Adventurer

Radiant Solar

Sefris of the Hidden Ways

Fiend Hunter

Ravenloft Adventurer

How it works

1. Cast Fiend Hunter by paying its mana cost.
2. When Fiend Hunter enters, it and Radiant Solar trigger.
3. Resolve the Fiend Hunter trigger, exiling Ravenloft Adventurer.
4. Resolve the Radiant Solar trigger, venturing into the Oubliette room, causing you to discard a card and then sacrifice Fiend Hunter.
5. When Fiend Hunter dies, it triggers, returning Ravenloft Adventurer from exile to the battlefield.
6. When Ravenloft Adventurer enters, it and Radiant Solar trigger.
7. Resolve the Ravenloft Adventurer trigger, venturing into the Cradle of the Death God room, creating a 4/4 legendary The Atropal creature token and completing Tomb of Annihilation.
8. If you control two or more The Atropal tokens, put all but one into your graveyard due to the legend rule.
9. Sefris' second ability triggers, returning Fiend Hunter from your graveyard to the battlefield.
10. When Fiend Hunter enters, it and Radiant Solar trigger.
11. Resolve the Fiend Hunter trigger, exiling Ravenloft Adventurer.
12. Resolve the Radiant Solar trigger from step 10, venturing into Tomb of Annihilation and into the Trapped Entry room, causing each player to lose 1 life.
13. Resolve the Radiant Solar trigger from step 6, venturing into the Oubliette room, causing you to discard a card and then sacrifice Fiend Hunter.
14. Repeat from step 5.

This clever loop exploits the endless entrance and exit of Fiend Hunter by using Radiant Solar's triggers to rapidly progress through dungeons. As you cycle through the Tomb of Annihilation, the legend rule forces extra The Atropal tokens into your graveyard, which conveniently satisfies Sefris of the Hidden Ways's resurrection condition—with the added bonus that Ravenloft Adventurer is safely tucked away in exile to be freed whenever Fiend Hunter leaves the battlefield, keeping the engine running indefinitely.