Just out of curiosity, what are your plans for the Abyssal Mauler (I think that's the name). IIRC, that's the monster everyone says DMs only use to kill players.
I think it's something like a CR 2. For the most part, everything is in line with its CR except for its ability to do 2d8 damage to someone automatically if they drop them below 0 HP. Basically, if you get dropped, statistically speaking, you die.
Higher CR or remove the ability?