A weapon, sealed within a stone with a magic spell, so that only a pure-hearted individual that the sword has chosen may pull it free. Over many centuries, the rock has hardened around the blade; even if one is chosen by Excalibur, their strength will still be put to the test. There is a spirit - named Excalibur after the sword she is contained within - placed there by Merlin to serve as a guide for the chosen one in his stead; she will awaken when the blade begins to be drawn from the stone.