Boiled One Add-on 1.21+

Boiled One is an ethereal horror game with unique monsters that will give players a terrifying and challenging experience. Naturally, the developers of mods decided to add all this to Minecraft so that users could enjoy sleepless nights in creepy nightmares. A creepy monster with unusual abilities will appear in the game.

Features
Custom screamer animation
Attack mode increases movement speed randomly
Only 1 mob appears in the world at a time
The monster kills the player instantly

The add-on will work with other builds. It's better to watch a short video to better understand.