Lafrenia

- He trips you when you're carrying a bucket of water and laughs a lot about it. And if you leave soup or porridge outside, he'll pee in it and it will spoil. And if you don't go to bed on time or don't do your homework, he'll torment you, - Mira nodded knowingly. - Our cook called him the Mischief-Maker. He caused them a lot of trouble.

— Yes, that's him. Also, he's a big opponent of technology and sometimes brings trees to life to teach a lesson to the inhabitants of cities where scientific progress is most noticeable. They are also called Mischief-Trees, only this time with a lowercase letter. They are quite dangerous creatures, but their bark can be used to make magical scrolls and books, and therefore is very useful for people in my profession. Look, here.
Misha opens the encyclopedia to one of the pages and shows Mira.

Mischief-Tree Damage: 200, paralysis, injury. Range: 5 Health: 1500 Defense: 100 Accuracy: 10 Evasion: 0 Speed: 10 Will: 30 OD: 0 Curses everyone who is more than 5 tiles away from it (all rolls are minimal, 50% chance of a critical failure of any action). Poisons everyone within 5 tiles of it.