Definitely one of the darkest and slimiest of the original series, whatwith the imagery of the Glus and the Maze (great originality with the dripping walls slowly sealing the victims in place). The visuals of The Glus are especially creepy, kudos to Rodda. And while the pirates are a bit one-note, they add a more relatable human villain element to contrast all the monsters and such. The River Queen steamboat was a fun touch. I was imagining a certain episode from Over the Garden Wall during the boat scenes though of course lacking the whimsy of that show.

Also, I do love the introduction of the Ols, who play a big part in the overall story. They're the kind of villains that insert that feeling of mistrust through every following scene: "is this character reeeeally the character we've known these past few books?" Great writing device, can't let the readers become took complacent.