Guinevere Jones S02E12 - Darkness Falls

Having used Merlin's Stone to save Karen, Gwen attempts to return the crystal to Merlin's time through Faerie, but O'Leary intervenes and gives the crystal to Morgana. But in a turn of events that surprises even O'Leary, O'Leary helps Gwen escape when Morgana attacks her. Gwen and O'Leary return to the 21st century to find that Morgana has ruled as an immortal for 1500 years. The world, including all of Gwen's friends, suffer under Morgana's tyranny - and Gwen herself has been declared an outlaw for practicing magic, which in this reality is preserved for Morgana alone.