Ever wonder why the Blood Elves (Horde) kill King Kael’Thas Sunstrider and his Blood Elves?
Or why are we fighting Kil’jaeden at the Sunwell Plateau if the Sunwell is gone since Warcraft III: Reign of Chaos?
Or what kind of magics will Blood Elf mages use now that Kael’Thas and his people has been killed?
Read up an article that recaps the events of Warcraft Manga: The Sunwell and the events of the Burning Crusade expansion. The article explains all those questions using lore from both sources. The article is only meant to those who do not mind spoilers from the Manga.