Complex sentence: He enlists the help of all the gunters in the OASIS to launch a coordinated assault on the corporate forces, during which all the avatars are killed before Parzival solves the final puzzle with the help of Aech and Art3mis.
Split into simpler sentences: He enlists the help of all the gunters in the OASIS to launch a coordinated assault on the corporate forces, during which all the avatars are killed except for Parizal. He then solves the final puzzle with the help of Aech and Art3mis.