Seeing some discrepancies as to whether it is Monstrox or Monstrux.
Forgive me if i am late to this, but just to catch up and see where everyone is;
Potential image of Monstrox’s human form from ‘The book of Monsters’

- Monstrox is the necromancer who caused Merlock to see all the evil in books as a ‘last resort’ to defend the kingdom
- Monstrox and his army were sealed in books
- The Book of Monsters is Monstrox, who consumes the other books to gain power
- Monstrox attempted to free himself at the end of season 2 by taking over ‘Clay’, however was seemingly defeated before this
- Monstrox however was not defeated, but instead freed from his book imprisonment as shown via his face appearing in the fireworks
- Its possible Jestro could be the only one who see’s Monstrox OR that Monstrox is still linked to Jestro OR simply that the others didn’t notice the face in the clouds
So its very likely that Monstrox will be the main villain of Season three with the group having to team up and work with Jestro (probably training him up to fight as a Knight with them) as they’ll have to face a reborn Monstrox and his army.
Alternatively it’ll be cancelled like Bionicle…