Plot summary
Ichabod identifies the deity summoned by Pandora as a Sumerian God known only as 'the Hidden One.' Having witnessed the Shard back when it was in Colonial hands, he realizes they need the casing it was in to draw it out of Jenny. Pandora reveals she is not Greek, but a Sumerian sorceress who has spent centuries gathering magic to revive the Hidden One, who she refers to as her "husband." While Ichabod and Joe distract them, Abbie starts draining the Shard's power into the casing. When the Hidden One destroys the casing, she takes the pieces and, holding them together, finishes the process. But now it is full of unstable energy and about to explode, so Abbie takes it through Pandora's tree and into a portal to another dimension. The resulting energy release apparently destroys Pandora's box and her tree, leaving Abbie's fate unclear.
Credits
Adapted from Wikipedia contributors, Sleepy Hollow season 3. HTML formatting and reference markers removed.