Complex sentence: When he finds the Tomb and defeats Acererak, the lich of the module, at a challenge involving the "Joust" video game, he is awarded the Copper Key, and pursues his next puzzle clue at the "Dungeons of Daggorath".
Split into simpler sentences: When he finds the Tomb and defeats Acererak, the lich of the module, at a challenge involving the "Joust" video game, he is awarded the Copper Key. He pursues his next puzzle clue at the "Dungeons of Daggorath".