The Mystic Falls Codex

The leader of the witches who took Silas's side against Qetsiyah and were cursed to wander forever. Markos passes his consciousness from body to body across the centuries and finally, in 2014, gets what every Traveler since the beginning has been chasing: both living doppelgängers in one place at one time.

The spell breaks the curse on the Travelers and simultaneously unmakes every other kind of magic inside Mystic Falls. Vampires in the town start dying of whatever killed them originally. It is the most effective thing any villain in the franchise achieves, and it costs Bonnie and Damon their lives to reverse.