Circle of Cernunnos (alternateively named the circle of Cernunnos) was an artefact in the matrix.
It was an artifact that was sought by Mockingbird, and was in the possession of Man Kempner. Mockingbird ordered operatives to steal a painting from the digger in return for the Circlet.
Trivia[]
Cernunnos was the name of a celtic horned god of fertility.