Carl and Donut are both on the newly introduced leader board, but like everything else in the dungeon, that comes with a downside. Everyone in the top 10 now has a bounty placed on their head encouraging the other crawlers to take them out via PvP. Of course, the leader board is just another way for the alien corporation running this apocalyptic game show to make money, and various sponsors now vie for the rights to each crawler. Carl and Donut both get sponsored, which opens up the possibility of sponsor and fan provided loot boxes, which they are both going to need. The 4th floor is known as the Iron Tangle, and it was clearly designed to disorient the crawlers. It is a mess of a multi train underground railway system with numerous tracks and junctions that intersect in an unpredictable way. Each group of crawlers arrives on the floor in a train filled with monsters, and more monsters get on and off the train each time it arrives at a new station. It makes you wonder what happens if the train gets to the end of the line? 

The fourth floor of the dungeon is way more complex than any before it, and Carl fights back against the complexity by starting up a giant group chat between players. His hope is that players on various train lines can help share information about the stations and junctions so that they can solve the puzzle together. Of course, anyone who has played an MMO knows how that will go, and it winds up being a combination of excellent information with vitriol and arguments. Toss in the bounties and the artificial motivations of the leader board, and some of the other crawlers become just as dangerous to Carl and Donut as the dungeon bosses. Katia, a doppleganger who joined their party in the last book, plays a bigger role and starts to catch up to Carl and Donut in levels. The title of the book also refers to an item that Carl receives in a fan loot box which opens up a whole other meta level of story. The cookbook is a collection of information from crawlers in prior dungeons and it provides Carl with secret insights into how the dungeons work. This enables him to fight back against those running the dungeon, as long as he can keep it secret from the constant scrutiny.

This one was fun, but the level design was a bit too complex for my taste, even if that complexity did give Carl an excuse to figure out how the NPCs actually work. The audiobook version continues to be a great listen with Jeff Hays doing an excellent job on the narration.