Activate Emiel the Blessed by paying 3, blinking Prosperous Innkeeper.
When Prosperous Innkeeper enters the battlefield, it triggers twice, and Preston trigger twice if it has power 2 or less, or once otherwise.
Resolve both Prosperous Innkeeper triggers, creating two Treasure artifact tokens.
Resolve the first Preston trigger, creating a token copy of Prosperous Innkeeper that is a 0/1 Illusion.
When the Prosperous Innkeeper token enters the battlefield, it triggers twice, creating two Treasure tokens.
Repeat from step 4 for the remaining Preston trigger, if applicable.
Activate three Treasures by tapping and sacrificing them, adding 3.
Repeat.
This clever loop begins by using Emiel the Blessed to repeatedly blink Prosperous Innkeeper, a creature whose low power allows its entry triggers to be doubled by Delney, Streetwise Lookout. Every time the Innkeeper (or a copy) enters the battlefield, you net a bounty of life and Treasure tokens. Meanwhile, Preston, the Vanisher watches nontoken creatures arrive uncast, immediately generating an army of 0/1 Illusion token copies that restart the entire cycle of entry triggers and treasures.