Yes those robots can pack a punch. If they are really exoskeletons then there must be a person inside operating it. The other boss that can cause me trouble sometimes is the giant svirri, the big lizard. It's leap attack often catches me unprepared and can down me, it's quite strong.

What gets me most is the Shielding on bosses, you get a boss with all 3 Shields and before you can get one down and start healing from damage your already dead.

Still the Pacified Aurora Knight kills me or at least makes me kill my game, OP damage, Invulnerability, and Healers yeah this one is the biggest pain and always comes on floor 3 and therefore wastes the last 30-90 mins

funny you should mention the aurora knight -- one just killed me on floor 3 :)
but i suppose that's what you get when you are trying to advance past 97 when your character is 75

kind of frustrating but i think it's cool that it can be difficult

Punisher Exo:
1. When he raises his arm, dodge. Incoming aoe from above.
2. When he pulls his elbow to the back, dodge. Super punch incoming.

Pacified Aurora Knight:
I usually keep a spare Freeze accessory / weapon in the inventory. Equipping them before boss fight just to have Freeze Alment on my attacks / spells. Freezing the minions helps. The hard part is keeping them close together so that I can cleave all of them at the same time while dodging those hectic aoe boss modifiers.

with playing bleeding edge solo, around 1.5 mil crit and 70% attack speed, proper rage cost reduction and pacified aurora dies really fast, only threat is a punisher, but with good equ u dont even have to dodge him