|Although this article is based on canonical information, the actual name of this subject is conjectural.|
Shadow casters were images not unlike shadow puppets that were meant to be used for a shadow play.
During the battle against the First Evil, Robin passed the shadow casters to Buffy Summers. The casters were set in motion by Xander, with the help of Dawn, who read the instructions through a tome that came with the set. Once set, the shadow casters moved on their own accord and were able to create a portal through time and space, sending Buffy to the era of the Shadow Men, and leaving a demon in exchange.