The Balors in the Abyss really need some differentiation to show how dangerous they are.
I got rocked by a creature marked Demon (Balor) because it had +58(!!!) to hit, IKD, and a powerful demon summon. It didn't have anything on it to differentiate it from any normal Balor or even a Balor Lord.
For reference, there were both Balors and Balor Lords a zone across. Both types of balor went down in one or two rounds and felt about equal in strength to each other (which doesn't seem right to me, given that they're supposed to be the strongest demons, but I digress). This gave the false impression that this Balor that I encountered was no different and so I didn't prepare as much as I should have before engaging it.
I don't want this balor nerfed - it's good that it's an actual threat since that's what balors should be! I just want it to be absolutely clear to a player that's going to engage it that the balor in question is more dangerous than others of its kind so that preparations can be made before fighting it. Give it a name. Give it literally anything to show the player the danger that they're in if they face it.
Don't just give it a generic name and dump it next to a zone where identical mobs are far less dangerous and trick the player on an OOC level into thinking that this mob is as much of a chump as the identical mobs are.