Preston, the Vanisher + Delney, Streetwise Lookout + Sefris of the Hidden Ways + Thermopod + Aarakocra Sneak

Preston, the Vanisher

Delney, Streetwise Lookout

Sefris of the Hidden Ways

Thermopod

Aarakocra Sneak

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

This engine transforms a completed dungeon into an endless, self-sustaining loop of exploration by leveraging Delney, Streetwise Lookout to double every creature-based triggered ability. When Sefris of the Hidden Ways brings back Aarakocra Sneak, Delney makes both the initiative trigger and Preston, the Vanisher's copy effect trigger twice. While Thermopod sits quietly ready to sacrifice creatures for red mana to keep the engine fueled, Preston turns those entering threats into 0/1 Illusions that continuously re-trigger the initiative and blast you straight through the Undercity dungeon over and over again.