Preston, the Vanisher + Delney, Streetwise Lookout + Sefris of the Hidden Ways + Bloodflow Connoisseur + Vicious Battlerager

Preston, the Vanisher

Delney, Streetwise Lookout

Sefris of the Hidden Ways

Bloodflow Connoisseur

Vicious Battlerager

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

This magnificent loop relies on Delney, Streetwise Lookout to supercharge your engine, doubling both Sefris of the Hidden Ways' dungeon completion triggers and the creature abilities of your low-power threats. When Sefris recurs Vicious Battlerager from your graveyard, its initiative-taking entry and Preston, the Vanisher's Illusion-copy generation both trigger twice. By sacrificing Vicious Battlerager to Bloodflow Connoisseur while holding priority, you set up a cascade of entering tokens that repeatedly ventures through the Undercity dungeon, unlocking every single room and restarting the entire cycle infinitely.