Honestly, I think my main beef with the fight is that the intended 'clever' way doesn't make much sense to me thematically. Firstly, while I am not an expert on the physiology of giant spiders, I expect with 8 fairly flexible legs it should be able to absorb falls pretty well and not take as much damage as it does. Secondly, it's a phase spider - it could simply phase/teleport while falling.
Okay that ... is a fair point
At least about the phasing. I also am not an expert on spiders (of any size) but I suspect that one the size of the matriarch would be impossible in normal gravity anyway, so all bets are off as to how it would absorb falls as we're working according to the laws of high fantasy rather than physics already!
