Preston, the Vanisher + Delney, Streetwise Lookout + Sefris of the Hidden Ways + Umbral Collar Zealot + Underdark Explorer

Preston, the Vanisher

Delney, Streetwise Lookout

Sefris of the Hidden Ways

Umbral Collar Zealot

Underdark Explorer

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 Underdark Explorer from your graveyard onto the battlefield.
5. When Underdark Explorer enters, it triggers once and Preston triggers twice due to Delney.
6. Holding priority, activate Umbral Collar Zealot by sacrificing Underdark Explorer.
7. Resolve a Preston trigger, creating a token copy of Underdark Explorer that is a 0/1 Illusion.
8. When the Underdark Explorer token enters, it triggers twice due to Delney.
9. Resolve the Underdark Explorer token triggers, venturing into Undercity twice.
10. Resolve the second Preston trigger from step 5, creating a token copy of Underdark Explorer that is a 0/1 Illusion.
11. Repeat steps 8 and 9 one additional time.
12. Resolve the Underdark Explorer trigger from step 5, venturing into Undercity and completing Undercity.
13. Repeat from step 2.

This elegant loop transforms the completion of a dungeon into an infinite engine by leveraging Delney, Streetwise Lookout to double Sefris of the Hidden Ways' reanimation triggers. When Sefris pulls Underdark Explorer back from the graveyard, the Explorer's initiative-taking entry pairs with Preston, the Vanisher to churn out 0/1 Illusion token copies of the Explorer—with Preston's triggered ability also doubled by Delney. Umbral Collar Zealot then steps in as a clean outlet to sacrifice the original Explorer in response, fueling a sequence of dungeon completions that repeatedly reset the entire cycle for boundless value.