Shadow of the Elves S01 E03 The Master Builder

One day, the Elf inventor, Snakehammer, is hit by a falling chestnut and loses his memory. The trolls "adopt" him - in return, he constructs an enormous machine, which paves the way to erecting a new city, "Trollopolis". Thalia and Daiman's efforts to stop Snakehammer and his machine fail miserably, but when Snakehammer regains his memory, he realizes that he must quickly reverse the machine to save the Meadowlands.