I'm not sure if this is a bug or if it is intended, so I made the post in general feedback, but feel free to change it if it's not in the good place.
Recently, when dungeoning, I've been trying to counterspell the bosses dungeons. Malthor, Prisoner-Slayer and the Fire Cave boss are the ones I tried it against. Everything I had a mordenkainens disjunction ready, and made all what should be done to be able to counter their spells, but it fails every single time. Were their spells given at feat, meaning we can't counter them? If that's the case, what was the reasoning behind it?