Preston, the Vanisher + Delney, Streetwise Lookout + Sefris of the Hidden Ways + Thermopod + Seasoned Dungeoneer

Preston, the Vanisher

Delney, Streetwise Lookout

Sefris of the Hidden Ways

Thermopod

Seasoned Dungeoneer

How it works

1. Complete a dungeon.
2. Sefris' second ability triggers twice due to Delney.
3. Resolve the first trigger, returning up to one other creature from your graveyard to the battlefield.
4. Resolve the second trigger, returning Seasoned Dungeoneer from your graveyard onto the battlefield.
5. When Seasoned Dungeoneer enters, it triggers once and Preston triggers twice due to Delney.
6. Holding priority, activate Thermopod by sacrificing Seasoned Dungeoneer.
7. Resolve a Preston trigger, creating a token copy of Seasoned Dungeoneer that is a 0/1 Illusion.
8. When the Seasoned Dungeoneer token enters, it triggers twice due to Delney.
9. Resolve the Seasoned Dungeoneer token triggers, venturing into Undercity twice.
10. Resolve the second Preston trigger from step 5, creating a token copy of Seasoned Dungeoneer that is a 0/1 Illusion.
11. Repeat steps 8 and 9 one additional time.
12. Resolve the Seasoned Dungeoneer trigger from step 5, venturing into Undercity and completing Undercity.
13. Repeat from step 2.

This intricate engine transforms a single dungeon completion into an endless loop by leveraging Sefris of the Hidden Ways and Delney, Streetwise Lookout to endlessly resurrect Seasoned Dungeoneer. Because Delney doubles Sefris's triggered abilities, a single completed dungeon brings back both a fodder creature and Seasoned Dungeoneer simultaneously, immediately retaking the initiative and venturing further into the Undercity. Meanwhile, Preston, whose own triggers are also doubled by Delney, endlessly duplicates the entering Dungeoneer into fragile 0/1 Illusion copies that feed right into Thermopod for red mana and sacrifice fodder.