THE COVEN. Buffyverse.

A group of powerful British witches (never actually seen on the series) who confer their collective power on Giles in order to combat Dark Willow (in "Two to Go" and "Grave").

As Season Seven begins, Willow is in England with Giles and The Coven as she seeks to recover from her experience with the Dark Side. Consulted by Giles periodically throughout the season, he seeks their help again (in "Chosen") when the decision is made to use Willow's magic  to infuse the power of The Slayer in all Potentials through the conduit of The Scythe.

--David Lavery