For the first few rounds of the fight, players other than the "chosen" one can blade others and place traps on the Snow Queen. At some point, you are never allowed to cast a blade or trap again, or she will say "Bad choice, chosen one!" and cheat-cast the blizzard spell + 3x100% protected shields that she casts when the chosen one does something wrong. Drain health spells don't count as a hit when chosen, the same cheat-cast comes up. I'm 100% sure I'm missing some, but the rules seem to change from the beginning of the fight to the middle/end (I've never actually been able to figure out how to beat her because of this).
I have a screenshot from her with 31x100% protected shields, and this is after she removed some. Is she really intended to not let anybody cast anything at any time, except the chosen one, and they can't use drain health or AoE spells?
My friend and I are on Snow Queen/Crypt of Tales for our 5th wizard sets (we have 6 maxes on mult accounts) and always were able to get through the entire dun series. Some took a few tries to figure it out but we always got it down expediently.
This time spent like 2.5 hours on Snow Queen, bailing twice to reset and try the above strategies. She has a new trick in spring 2022 - a -90% plague that we don't even see casted. She did this 2x our last run and by that time it was late and she started going all random like before doing the triple shields no matter what, having being chosen when the chosen player cannot see aura we could or no one chosen for multiple rounds, just boss taking forever with 3x shields over and over and over like a loop....
We are long term players very efficient and this thing just drove us nuts with the absolute randomness and total constant debuff of us and stuff like "You Are the Chosen One" then Queen stuns entire team then boom! nope not chosen anymore, over and over. And then strips all blades leaves a new -90% aoe debuff.
Got sick of banging our heads against the wall and called it a night.