Preston, the Vanisher + Delney, Streetwise Lookout + Sefris of the Hidden Ways + Altar of Dementia + Undermountain Adventurer

Preston, the Vanisher

Delney, Streetwise Lookout

Sefris of the Hidden Ways

Altar of Dementia

Undermountain Adventurer

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

This elaborate loop is anchored by Delney, Streetwise Lookout, whose passive ability acts as an amplifier to double up key triggers for your low-power creatures. When you bring back Undermountain Adventurer using Sefris of the Hidden Ways, Delney ensures that Preston, the Vanisher creates multiple uncast illusion copies, while simultaneously accelerating your dungeon progression through the initiative. Altar of Dementia provides the necessary sacrifice outlet to feed this engine, letting you bin creatures and continuously cycle Undermountain Adventurer to infinitely complete dungeons and amass overwhelming value.