Sword Art Online Progressive Canon of the Golden Rule, Vol. 2 (manga‪)‬

After a close call with Morte and his PK gang during the Stachion questline, Asuna and Kirito make their way toward the front line. Trekking through the harsh desert, they arrive at the dark elf fortress Galey—where they’re reunited with their old companion, Kizmel, who gives them a clue about the poison pick Morte used in his last attack. But that lead will have to wait, as the three must retrieve the floor’s sacred key before the fallen elves bring their nefarious scheme that much closer to fruition…