Call of Cthulhu

School divination [mind-affecting]; Level 5


Casting Time 1 hour (2 phases of 30 minutes)
Components V, S
Optional Components F (the R’lyeh Tablets give a +5 insight bonus on ritual skill checks)
Skill Checks Knowledge (arcana) or Profession (Yog-Sothothery philosopher) DC 20, 1 success (diagram); Knowledge (planes) or Profession (Yog-Sothothery philosopher) DC 20, 1 success
Range personal
Diagram caster stands within a circle of markings and engravings incorporating non-Euclidean shapes and angles
Target caster
Duration 1 month/level


This ritual provides Great Cthulhu with knowledge of the caster and access to the caster’s mind. Nothing appears to happen upon successful completion of the ritual, but Cthulhu will later communicate with the caster through dreams or nightmare visions of sunken R’lyeh. Those who cast this ritual that do not worship Cthulhu automatically gain a major insanity or are drawn to cults of Great Cthulhu.

If the caster sleeps on the circle then they are guaranteed to receive messages from Great Cthulhu or one of the star spawn. Non-cultist casters who sleep on the circle can be psychically attacked by a star spawn on the same planet, and their location is made known to the nearest cult of Great Cthulhu.

Section 15: Copyright Notice

Sandy Petersen’s Cthulhu Mythos, © 2017, Petersen Games; Authors: Sandy Petersen, Arthur Petersen, Ian Starcher.

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