Sefris of the Hidden Ways + Radiant Solar + Progenitor Mimic + Synth Infiltrator

Sefris of the Hidden Ways

Radiant Solar

Progenitor Mimic

Synth Infiltrator

How it works

1. Put any nontoken creature onto the battlefield.
2. When the creature enters, Radiant Solar, Synth Infiltrator and Progenitor Mimic each trigger.
3. Resolve the Radiant Solar trigger, causing you to venture into Tomb of Annihilation and into the Trapped Entry room, causing each player to lose 1 life.
4. Resolve the Synth Infiltrator trigger, venturing into the Oubliette room, causing you to discard a card and then sacrifice Radiant Solar.
5. Resolve the Progenitor Mimic trigger, venturing into the Cradle of the Death God room, creating a 4/4 legendary The Atropal creature token and completing Tomb of Annihilation.
6. If you control two or more The Atropal tokens, put all but one into your graveyard due to the legend rule.
7. Sefris' second ability triggers, returning Radiant Solar from your graveyard to the battlefield.
8. Repeat from step 2.

This loop is a masterclass in dungeon-crawling synergy, turning a single creature entry into a relentless cycle of room completions. Whenever any creature enters the battlefield, Radiant Solar, Synth Infiltrator, and Progenitor Mimic all trigger to rapidly propel you through the Tomb of Annihilation. Synth Infiltrator sacrifices Radiant Solar along the way, which immediately sends it to the graveyard and triggers Sefris of the Hidden Ways' second ability. Once the dungeon is completed by Progenitor Mimic, Sefris resurrects Radiant Solar back to the battlefield, setting the stage to loop the whole process over again.