Time to wrap up my survey of Monsters of the Multiverse with the final category: demon lords. My look at archdevils went so quickly, I was tempted to go ahead and lump both groups of archfiends into one post, but demon lords turned out to be more complicated. As with the archdevils, I’ve placed these notes behind spoiler tags.
One note that applies across the board is that references to insanity have been eliminated, so that any regional effect of a lair characterized as “Madness of X” is now called “Beguiling Realm” or “Corrupted Nature” and given the simple effect of imposing advantage or disadvantage on certain skill checks, or it’s simply deleted. Regional effects usually kick in before combat begins, so these changes mostly apply to situations occurring before or after a battle, but they can also alter the outcome of a mid-combat parley or keep an unconscious and dying character from being stabilized.