Question: does asriel die in his dark materials?
Answer: As his army fought the armies of the Authority and the Church, Mrs Coulter tricked Metatron into trying to kill Lord Asriel and take Lyra's dæmon as he was on the edge of the Abyss. Lord Asriel and Mrs Coulter sacrificed themselves by taking Metatron down with them, falling in the Abyss as ghosts for eternity.