There's no tome-scumming, and crafting is the most effective way of building damage and physical resistance (and magical aswell but it's expensive and only worth it at some specific moments).
I did honor mode, and yeah she did oneshot one of my chars. A few bosses have a lot of initiative, and she's the most fearsome of them I think.
To deal with her potions, you can use the witch skill that changes healing into damage, but unfortunately I couldn't test it as I managed to stun her and oneshot her (after a rez).
I went the offensive route, but I added a few CONST from that point (Her, Dark knights and some other fights have opponents that hit like trucks) so I'm mostly sure I stay alive the first round.
I don't know what would be the point of a tank, because I had a look at the armor/resist stats and they don't really shine on a tank. The armor on leather and plate is oftentimes very similar (if not identical). But cloth is less good, so it's best to have STR boosting items on your mage so can wear plate (and 1H + shield as simple stat-item, not to strike with it).
The "tank" build for me is mostly for exploration (just wander carelessly with 100% resist fire and maybe poison if you pick zombie).
