Avatar of the Black Goat with a Thousand Young

9th-level transmutation (formula)

Casting Time: 25 hours (5 phases of 5 hours and fails automatically if interrupted when cast as a formula)

Range: 60 feet

Components: V, S, D (5-foot-wide circle of blood around target), L (area under obscene fertility rites of Shub-Niggurath), SC (0 to 9, which must have proficiency in Religion or Yog-Sothothery and chant from text; +1 bonus on formula ability checks per 3)

Formula Ability Checks: Intelligence (Nature) or Wisdom (Yog-Sothothery) DC 27 (diagram), Intelligence (Religion) or Wisdom (Yog-Sothothery) DC 27, Intelligence (Religion) or Wisdom (Yog-Sothothery) DC 27

Formula Backlash: Three levels of exhaustion and 9d4 psychic damage

Formula Failure: Second-degree insanity or indefinite madness, and magically frightened for 10 days

Duration: Instantaneous

You bless a willing or incapacitated creature you can see with Intelligence 5 or higher that is not a construct or undead. The creature becomes an avatar through which Shub-Niggurath can manifest. An unwilling target can negate the spell’s effect with a successful Constitution saving throw. As you complete casting this spell, you can choose for a daughter of Shub-Niggurath to burst from the target, slaying it. The daughter has some superficial features of the target but is not under your control.

It serves Shub-Niggurath’s will, which is as likely to entail feeding on cultists as fighting alongside them.

Rather than summoning a daughter of Shub-Niggurath, a dark young or servant of Shub-Niggurath can magically command the target to bring forth the Outer God herself at any time as an action with a DC 30 Intelligence (Religion) or Wisdom (Yog-Sothothery) check. On a failure, the servant issuing the command takes 9d6 psychic damage. On a success, the servant takes half as much damage and Shub-Niggurath’s influence escalates to stage 3 until her whims draw her elsewhere or she is defeated or banished.

This causes Shub-Niggurath’s new nucleus to explode forth from the avatar, slaying it. Unless Shub-Niggurath would otherwise be at influence stage 3, she falls back to influence stage 2 when her nucleus is destroyed. Only a wish or divine intervention can remove this avatar status from the target.