User blog comment:TheGreatLegend/Arthur's Death/@comment-67.184.200.91-20111130011646

It's based on Arthurian legend. According to Arthurian, Mordred kills Arthur. Now although Mordred will eventually kill Arthur there is no indication as when in the series. It's most likely after Albion is united and after Merlin and Arthur's destinies have been fulfilled when Mordred will then kill Arthur.