Add a mangroove boss

Have you ever got bored from beating the warden?, well.... introducing mangroove boss, it has 1/1000 chance for it to spawn in the mangroove biome and, sometimes on 1/2000 chance on muddy ruins, with better loot like, Efficiency V book, Sharpness V book, and etc..., Buuut... there is new mobs and blocks like, muddy shapeshifter, it can shapeshift into a mud block or muddy mangroove roots it can sometimes jumpscare you out of nowhere, and lastly poisonous mud it poison you temporarily (10 seconds), well people.., that's all of that tysm for reading this