Acererak’s Baleful Eye

While attuned, this large multifaceted blue gem grants truesight truesight out to 30 ft. and allows a spell caster to concentrate at two spells at the same time. When you fail a concentration check, both spells fail. To attune to this gem, a creature must remove one of it’s own eyes and insert the gem into that empty socket.

Notes: Sense: Truesight, Detection