This pack includes:
Scamp
Imp
Succubus
Demon Lord
Demon chest with key
1 sword
4 crafting materials
1 demon helmet for /hat
All skill models
Mythicmob files
BOTH ItemsAdder and Modelengine configs

Mob special behaviors and abilities:

Scamp:
Fast evasion
Fireball
Melee attack on approach

Imp:
Flying
Double fireballs
Picks up and throws players

Succubus:
Disables with a kiss
Sonic wave scream
Whips and sets on fire
AoE attack

Demon Lord Ogmorath:
Slash followed by cone of flames
Smash lands with wave of flames
AoE tail and slash
Grabs and stabs player
Throws giant fireball
2 melee variations

Demon chest:
Right click on chest with demon key to open

Including Dungeon Schematic As well

Dependencies: Mythic Mobs, LibsDisguise, ProtocolLib, Modelengine or ItemsAdder
Tested on Minecraft Java
1.19.2