New Mob: King Demon 😈
He would be an elite demon that spawns only at the centre of d4 after killing x demons. Most of demons at centre merge to him (as every elite). Maybe could be joined with 2 barlogs. It would need to be up for several minutes giving player enough time to kill it. (Make a treshold that when in less than 10% can't despawn)
He could cast multiple mfs at once. It should always drop something (piece of armor at least)
Make it strong enough that a solo player cant claim it just like currently d4 gold chest