The Yellow Petition

Call Hastur: Calls the deity to nine large blocks of stone arranged in a V-pattern (always a sign of cult activity!) Each of the stone blocks needs a volume of nine or more cubic yards.
The spell can be cast only on clear nights when Aldebaran (in the constellation of Taurus) is above the horizon (roughly month 3 or 10). Each byakhee present during Call Hastur adds a further 10 percentiles to the chance of success.
If 5 points of POW have been sacrificed into each of the stone blocks, so that all are enchanted, the stone V adds 30 percentiles to the chance to cast Summon/Bind Byakhee.

Related Deity/Higher Power

Hastur, the Unspeakable

Material Components

Cost: 1+ magic points per person; 1d10 Sanity points (caster only)

Effect Casting Time

1-100 minutes