This gem appears to be a large blue sapphire that emits a soft glow around its dark core. It entombs the soul of a powerful white dragonborn sorcerer from Abeir named Yisar. If you are a sorcerer, dragonborn or dragon and come in contact with this gem, you immediately feel a strong and innate connection to it. You can attune to it by pressing it to the center of your forehead for an hour, whereupon it harmlessly embeds itself into your skull. It cannot be removed unless you are dead or choose to end your attunement, at which point it can be easily pried out, leaving no wound behind.

Mists of Yisar. While attuned to this item you can use it to cast Fog Cloud at will once per long rest at 9th level requiring no concentration, spell slots or components, and you can see normally through the fog it creates. Upon casting the spell this way, or at any time while the spell remains active, you can choose to concentrate on it. While concentrating, you can use a bonus action to resize the radius of the sphere of fog from its central point to any size between and including 20 and 180 feet. When your concentration ends, so does the spell. When the spell ends, the remaining fog is instantly drawn into the gem, which chills you to the bone and tugs at your life force. You must make a DC 22 Constitution saving throw, taking one level of exhaustion and 27 (6d8) cold and 27 (6d8) necrotic damage on a failed save, or half as much damage with no exhaustion on a successful one.

Yisar's Eternal Prison. If you die while attuned to this item, your soul becomes imprisoned within it and must be released before you can be resurrected. If your soul remains imprisoned for 24 hours, it is consumed by Yisar's and you can only be resurrected after Yisar is defeated or via a Wish spell.

Shattering or dispelling this gem releases the souls within it, and the soul of Yisar immediately appears in the nearest unoccupied space in the form of an Ancient White Dracolich with the ability to cast 9th level Fog Cloud at will. The gem then becomes a nonmagical blue sapphire.

Notes: by a sorcerer, dragonborn or dragon, Utility, Combat