Yeah it's not about your resistance after her debuff, a solo character can oneshot her at level 13 (I did twice her hp at 15) so it's all about surviving her first turn and then killing her before she can act again.
Oneshot her on Tactician? Lore seems pretty pointless when you use it to examine her before you fight and it shows her resistance hole of Frost but then it is instantly patched up with a permanent +100 resistance plus immunity to freeze cheese. I thought we'd moved on from Kangaxx-like cheesy fights from BG2 where you have to know exactly which moves to make after the millionth time dying to cheese. Cheese. Oneshot cheese and cheesy auras and resistance cheese.
I'm trying not to use Lone Wolf anymore, but as soon as I come across this nonsense it makes me wish I hadn't switched.
