A companion reference book to Rick Riordan's Magnus Chase and the Gods of Asgard trilogy, framed as the official handbook handed to newly fallen heroes when they check in to Hotel Valhalla, the afterlife resort for Odin's chosen warriors. The conceit: Helgi, the hotel's manager for more than a millennium, grew tired of fielding the same questions from confused new arrivals, so he commissioned this guide, leaving much of the writing to Hunding, the bellhop who has served since the year 749. Through their irreverent, in-world voices the book profiles the major gods, giants, dwarves, elves, and monsters of the Nine Worlds of Norse mythology. Genuine myth is mixed with comic invention and delivered through varied formats, including dossier-style stat blocks, interviews, first-person confessionals, mock newspaper articles, and short anecdotes, with black-and-white interior sketches and a pronunciation-guide appendix at the back. The result is a browsable supplement rather than a plot-driven novel: it expands the mythological world that Magnus Chase inhabits, supplying the lore that would have bogged down the main adventures. Aimed at the same middle-grade readership as the trilogy, it is best enjoyed alongside the novels, deepening a reader's grasp of Asgard, Valhalla, the einherjar, and the wider Norse cosmos. Cover art is by John Rocco, and an audiobook edition is narrated by Kieran Culkin.