Ziggurat

The Ziggurat is an ancient structure below Whitestone, formerly a temple to Ioun. After the Briarwoods seized Whitestone, they took over the Ziggurat and prepared it for a ritual to Vecna. The Briarwood letters mention a manse inside the Ziggurat.

Although the Briarwoods' ritual did not completely succeed, it did leave behind a strange, hovering black orb that sucks in anything that touches it and disables all magic within a certain radius. Because this magic-syphoning orb provided protection from Scrying and dispelled any magical disguises, the Ziggurat was subsequently used as a war council room by Vox Machina and their allies in Whitestone.

Scanlan Shorthalt and Lionel Gayheart later discovered a second Ziggurat on the continent of Marquet, within the Smolder Crown Mountain, where Delilah had conducted a second (more successful) ritual.