Oh yes, give them all phasing as reaction, that would be total pain to beat.
Replaying these encounters when you already know the gimmick to beat them is dull.
I agree with this wholeheartedly. Though it’s not something new in games, isn’t it? For example with help of Dispel Magic spell you could render some nasty creatures that use magic weapons completely harmless and take your time to beat them to death (BG1). It’s a part of solving the combat puzzle and once solved there’s little left to replay. I’m fine with that you can burn the web and send her down, it’s quite satisfying btw. But after that I expect her to learn and adapt, not to repeat the same mistake that has just broken her quite a few legs.