Zariel in charge of Avernus, is ~new.
There goes Asmo jerkin' them dudes around again.
Mammon gets Tenser's as a short recharge and not a ritual (hmmm or not).
I suppose the crunch is interesting, more fluff oriented ... if you like post-Planescape.
While the Cultist stuff is dmfiat for npcs, a PC could use any 1 entry
as a guide to proper cult behavior + even a build substitution or 2.
Say like allowing the cult leader power during 2nd tier sometime.
Funny that Demogorgon is a Gnome's-voice-inside-my-head thang.
You think you're a big head don't you, but noooo you're just a little head.
Fraz's autodetect on Illusions and Hide guys, is just plain old bonkers.
Kinda specific for a Lair Action but in that ballpark. DM's should
Conj / Gate a Marillith or Nalfeshnee , because those are quite tasty.
You get to rock it ... until they show back up later with reinforcements.