Character Analysis
This dude sounds like the stuff nightmares are made of, and according to Grandma, Bahumat is "a powerful demon" who "terrorized the natives who dwelt in the region" (15.90). A bunch of Europeans managed to lock him up, and they built Fablehaven on the land that used to belong to him—apparently it's a Big Deal if Bahumat's released, since the demon'll terrorize everyone in reach.
When Muriel releases him, Kendra gets a glimpse of Bahumat:
The loathsome demon stood three times as tall as a man and had the head of a dragon crowned by three horns. The demon walked upright, possessing three arms, three legs, and three tails. Oily black scales bristling with barbed spikes covered its grotesque body. Malevolent eyes gleamed with wicked intelligence. (18.82)
Icky, right? Luckily for us, the fairies swarm Bahumat and bind the beast once more. This victory comes at a cost though, since Bahumat is taking down fairies left and right:
His great jaws clamped shut, tearing off the gauzy wing of a fairy with markings like a ladybug. (18.92)
Poor fairy. But once Bahumat is bound, with Muriel tied to him as well, we get the sense that the demon is no longer a threat… for now, at least.