The dungeon boss difficulty is all over the map. I think this is due, in part, to the encounter design team working in a vacuum compared to the class design folk.
Let's say you make a boss and decide to really make it melee unfriendly and encourage high movement and spreading out. In most games this would be a perfectly viable encounter design except for the fact that there are only TWO functioning healing spells and they require staying clumped around the boss in order to function.
Right now everyone is playing "Scissors" which is amazeballs against "Paper" but just plain terrible when coming against "Rock". Because you have so many people grinding out Seals in Epic Cloak Tower (aka free lewt central) they get a high enough gearscore to go to Tier 2 and promptly fall over dead on trash because 'charge in and spam AE knockback' is no longer the award winning strategy it was up till now.
Cryptic has been tight lipped about class fixes and design changes coming up, they most certainly have to be a thing that is coming but lord only knows how soon or what form these will take.
Some of the fights are straight up retarded. To take 2 recent examples, the last boss of the snow mountain area dungeon, a giant ice ogre and a large amount of his buddies. I tanked that, I sometimes spent up to 10seconds being CCed by repeated knockbacks and knockdowns. Fucking wolves, fucking golems and then the fucking boss itself. I can't guard everything(or much at all), I can't evade dodge and once I get CCed once I get fucking air combod like it's marvel vs capcom. Luckily every once in a while I manage to scrounge up full AP(fairly easily really), then it's CC IMMUNITY TIME, for 10secs. Fight was annoying as shit.
But apparently, they could do worse. I've tried 3 times to do the skirmish in the lava mountain area, retake the bridge or whatever. Last(I assume?) boss is 3 fucking fire giants at the same time, they can do a long range cone pull, a pbae knockback+residual fire dmg, a large normal giant swing attack(like the ogres do) and a strong localized punch that leaves fire shit on the ground plus one of them also do multiple fire circle shit on the ground. Every group disbanded after a bunch of wipes, shit didn't even look close, closest was 2 rogues trying to burn one mob down while the rest of the group was getting mowed down, the constant disables makes it impossible to do jackshit it seems. It's like you get hit by ONE thing, and you can't move until you're dead, which takes maybe 2seconds anyway, unless you're standing in the cleric circle but the cleric either dies, or you get moved out of the circle.
I mean I'm sure with a solid group these aren't so bad but in pubs it was a fucking mess, and what's weird is the rest of the place/game is fairly faceroll, but then suddenly assraping time. I assume in endgame it's the same shit but the encounter design is really retarded, it's the same shit over and over again(avoid ground, adds) and the only way to increase difficulty is to just turn all that shit to 11, by spawning dozens of elite adds, having massive ground aoes and adding a large amount of CC in the mix so you cannot avoid the adds or the ground all the time.
I'm probably done with the game anyway, I've seen all the content almost, still need to do last zone and 1dungeon, no point in grinding further, not a big fan of how the group dynamics work especially at higher level.