You have had a creature sealed within you by force or willingly fusing it with your soul.
Upon getting a Celestial, Fiend or Dragan of CR 25 - 28 sealed within you. You gain a small buff to your physical attributes (+8 to Strength, Dexterity and Constitution)
You can summon a spectral form of the creature that is sealed within you to surround your body as a bonus action. You can do this equal to your proficiency bonus per long rest.
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