Lightless arbor :
Sometimes the gloom screechers will just one-shot you.
I don’t mind difficulty, but I think that having a small chance to get one-shotted by things you won’t even see until they are on top of you is just bad game design (or maybe a bug?).
Boss fight is really hard, but that wouldn’t be too bad if it weren’t for the fact that if you die (and you will, often, unless if you are extremely well geared or play flawlessly for the entire fight), you loose all 100% of your progress.
Temporal Sanctum :
Well designed overall.
Just as with the case of the other dungeons, dying should be made less punishing.
It’s extremely frustrating to feel that you wasted 10-15 minutes of your life for absolutely nothing.
Pathing should also be improved, getting to the boss often feels extremely frustrating due to the number of blocked pathways and the length of the levels (that also applies to the other two dungeons.
Soulfire Bastion:
Very well designed overall, the only problem is that if you die you loose all progress, all souls, everything.
So you could very well end up having spent half an hour in there and you get nothing as a reward.
Overall, I believe the most important change that is needed is that if you die you are punished less severely.
Maybe make it so that you have to start at the entrance of the second level if you die to the boss- so that you have to run all the way back to the boss room - , if you die in any of the two levels, you have to restart at the entrance of that level, and for every death you take in the dungeon, the boss drops 10% less loot (additive over multiple deaths), or something along these lines.