Hexcalibur

S1, E54: Sabrina needs help on a Netherworld term paper. She sneaks into Zelda's prize possessions to look at a journal written by the famous Wizard, Merlin. But the fragile book crumbles upon Sabrina's touch. She goes back in time to visit the famous wizard in hopes of getting another copy and replacing it before Zelda finds out. But she and Salem go back a little too far and wind up in a time when Merlin and Arthur are the same age as Sabrina. Arthur pulls the famed Excalibur sword from a stone unaware that his jealous sister Morgan wants the sword for herself. Morgan plots to capture Sabrina and steal Excalibur. But Merlin comes to the rescue saving Sabrina, Arthur and Salem from Morgan's dungeon.