Character image 360x480 BoM

Monstrox Cloud

Human Form Monstrox

Years 2016
Set Appearances 70316 Jestro's Evil Mobile
70323 Jestro’s Volcano Lair
70352 Jestro's Headquarters
First TV Appearance All
Special Armor  ?
Follows Jestro (formerly)
Weapons & Gear Staff of Monstrox (formerly)
Quote "You see that, kid? You're good at something! You're good, at being bad."
Voice Actor Mark Oliver

The Book of Monsters (formerly known as Monstrox) is a sentient spellbook, and was Jestro's sidekick and mentor. At the end of Season 2, he was reborn as the Cloud of Monstrox.

Description Description

The Book of Monsters is not bad. He is terrible! Manipulative, power-hungry and really good at being mean to others. He is highly intelligent and filled from cover to cover with both horrible monsters and vicious plans to take over Knighton. Since he is just a book, he needs someone to perform the actual bad deeds for him. Someone he can lure with promises of power, manipulate with ideas of evil and shout insults at when it fails.


The Book of Monsters was once a necromancer named Monstrox, who terrorized Knighton with his dark sorcery. A member of the Wizards' Council, Monstrox experimented with dark magic, and discovered the Forbidden Powers, which he used to wreck havoc across the land. The Council was left with no other choice but to defeat him. The good wizard Merlok defeated Monstrox by turning him into a book, dividing most of his evil power among eleven other spell books, turning his original army into stone, and shrinking his castle to be placed inside a snow globe.

Although he knew that destroying the spell books would ensure Monstrox's eternal defeat, Merlok was reluctant to sacrifice sources of such potent (if evil) magic. He took the books (including the former Monstrox) to hislibrary, where they sat on a shelf for many years.

Season 1

Following his defeat, Monstrox bided his time and plotted revenge against the Kingdom of Knighton. Knowing that he still had some power even in his book form, he waited to be found by someone he could manipulate into acting as his pawn.

One day, Jestro found the Book of Monsters after storming off in a fit of embarrassment and fury about never being taken seriously. Sensing a perfect pawn at last, the Book manipulated Jestro into becoming a "bad boy", promising him tremendous power that would stop anyone from laughing at him ever again. With the Book's power, Jestro summoned a lava monster army ("The Book of Monsters - Part 1"), including a Book Keeper to hold the Book of Monsters so Jestro wouldn't have to. They then planned out multiple attacks on the Kingdom of Knighton, but were defeated. ("The Book of Monsters - Part 2", "Alliance of the Fortrex")

During the ensuing war, the Book of Monsters encouraged Jestro to seek out the other eleven spell books which contained his remaining power, explaining that he could perform new and stronger spells by consuming them. Despite the Nexo Knights' best efforts and a number of other setbacks (including Jestro himself returning to the side of good), the Book eventually succeeded, restoring Monstrox's full power. He promptly attempted to possess Clay, sending his army to delay the other knights when they arrived to save their comrade. The knights held their own against the lava monsters, but this only allowed Monstrox to reabsorb their energy, making him powerful enough to defeat them all in a single strike.

Just when all hope seemed lost, Clay was given the sword of Merlock by the Black Knight mech, who allowed himself to be sucked into Monstrox's mouth. Overcome by the pure magic energy, the villain exploded spectacularly, taking all of his summoned monsters with him and leaving only the charred cover of his book form. The Kingdom of Knighton celebrated Monstrox's defeat, but Jestro saw the former necromancer's face in a distant cloud, hinting at his survival.

Season 2

Unbeknownst to the kingdom, Merlock's sacrifice only served to destroy the Book of Monsters; the evil spirit within endured in the form of a living storm cloud. Enraged at yet another failure, Monstrox changed his plans from conquering Knighton to destroying it outright and mind controlled Jestro into becoming evil again. He then set about reviving his original army of monsters by using his new lightning abilities to reanimate their petrified bodies, all the while planning to unleash the Stone Colossus.


The Book of Monsters is a large brown book with a gruesome, living face on its cover. He uses a silk bookmark as a lizard-like tongue, and grows larger with every spell book he consumes.

Following his second defeat, Monstrox appeared as a dark grey storm cloud with his old face on the front. In this state, he can move independently, generate electrical bolts, and channel dark magic to animate unliving objects or corrupt other people.

He is very sarcastic and can easily get what he wants through persuasion. He can also play the harmonica, but he is an awful singer, according to Jestro.


TV series

Season 1

Season 2

Season 3

Season 4




  • LEGO Club Magazines


  • The Book of Monsters is likely a parody of the Necronomicon ex Mortis, or Book of the Dead, from the Evil Dead franchise.


Main article: Category:Book of Monsters images

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