The Innistrad Campaign
Born from ancient demon-worship, the Skirsdag are now a secret demon cult centered in the High City of Thraben. This secret organization has human members in all levels of the church, nobility, and the trades. Although small, it has been in existence for generations. When the demon Griselbrand rose in power to eclipse all other demons, the Skirsdag gained prominence as well. Griselbrand disappeared around the same time that Avacyn did, leaving the humans of the Skirsdag to further his ends in their lord’s absence.