Yellow Sign

3rd-level enchantment (formula, ritual)

Casting Time: 1 minute (5 phases of 2 rounds when cast as a formula)

Range: Touch

Components: S, M (special ink or tools worth 200 gp, which the spell consumes), D (up to 5 feet across, on object touched)

Formula Ability Checks: Intelligence with calligrapher’s supplies or painter’s supplies DC 15 (diagram), Intelligence (History) or Wisdom (Yog-Sothothery) DC 15, Intelligence (History) or Wisdom (Yog-Sothothery) DC 15

Formula Backlash: 3d4 psychic damage and one level of exhaustion

Formula Failure: Magically frightened for 1 hour

Duration: Until dispelled

You must worship Hastur or the King in Yellow to cast this spell; otherwise, it fails and you suffer the Formula Backlash if you cast it as a formula.

You create a Yellow Sign on the touched object. The Yellow Sign can only be noticed or identified by creatures with an insanity and creatures who have read the King in Yellow play or other sanity-threatening texts describing related entities. If a creature who noticed the Yellow Sign is not a worshiper of Hastur or the King in Yellow, that creature becomes frightened for 1 minute and must succeed on a Wisdom saving throw or be driven insane for 1 round.

While insane, it can’t take actions, it can’t use or understand language, and the GM controls its movement, which is erratic. On a 1 on the d20 roll for this saving throw, the temporary insanity is followed by a permanent second-degree insanity. The creature becomes obsessed with the Yellow Sign, the King in Yellow, and Hastur, eventually becoming a true cultist of the King in Yellow.

Sometimes the inscriber gets carried away in crazed artistry and makes it into an elaborate baroque sculpture or hides it such that it can only be seen as graffiti on multiple buildings from a certain angle. You can create a Yellow Sign larger than 5 feet across when you cast this spell as a formula by increasing the ability check DCs by 1 each per 5 feet of the Yellow Sign’s radius.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you can create a Yellow Sign with a radius of up to 5 feet, plus 5 feet per level of the spell slot above 3rd.

Section 15: Copyright Notice

Sandy Petersen’s Cthulhu Mythos, © 2018, Petersen Games; Authors: Sandy Petersen, David N. Ross, James Jacobs, Arthur Petersen, Ian Starcher.

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