I'm having the same problem. I've tried three different times now, with different tactics, and I get wiped out each time. Any tips would be appreciated.
There's two thing I did that let me clear the fight.
The first is the attack pattern. She starts with Behind Cover, but she loses it when she counters. So one of my first actors (a frontliner) would provoke a counterattack so the rest of the team could hammer on her. The other combatants aren't nearly as much of a threat, though if you wanted to you could blind her then mop up.
The second is gear. Between manor upgrades and locations, I had good access to steel and ironwood, and some access to magic wood and mithril. Pushing my team through a full gear upgrade closed the gap.
As a detail, bringing Zephyra is a huge help because her exclusive Wind Wall skill counters arrows pretty well.
For the record, I'm running a dominator/necromancer build, with an orc companion berserker/deathknight. I ended up training up a dragon knight to assist, and with those three plus Zephyra I cleared it pretty solidly.
Good luck!
My go to squad from years ago has always been 6 dragon kin. I get a dwarf or two with crit chance 20% for smithing, unlock battle smith, buy blacksmith and foreman, craft mithril heavy armour, heavy sword on my character, heavy crossbow on my starter slave, revert her from subordinate to slave, then back to subordinate (Since I can't get knight until I do that since knight is noble only and not accessible to slaves, so even though it shows subordinate, she's technically classified as a slave, thus the need to dungeon delve for the dominant shrine and break her will to use a writ) Then have three heavy crossbows in the back for arrow hail, with full legendary plate, three frontliners with heavy swords of legendary and just farm til they're where I feel comfortable, non-stop using cleave. I barely lose 3-5 hp against most enemies, including lich minibosses with bonus buffs. (Upwards of 1200 hp) And all my battle squad have over 300 hp in this setup. Also, humans became relevant now, since they can copy one unique racial class. I advise copying the dragon knight class. But you do you. I basically glide through any dungeon atm. I'm waiting til I have full gear before progressing with the story. And maximising my slave trader level. For maximum factor upgrades.
Sounds beefy! I have to admit that the orc berserker/deathknight doesn't hold well at lategame. Its bonuses can't really overcome its inability to equip shields, and with body mod for strong arms the ability to swing a two-hander plus have extra evasion and counterattacks is just too good. And I'm in a similar boat, unless I'm going up against bonkers boss battles my frontliners are only taking chip damage, so the other body mod options just don't hold up.
Also I've totally slept on the upgrades system until now, wish I'd been cranking out legendary quality iron gear back in early game.
One of the reasons for even trying this mission is so that I can progress the main story enough to get good gear. I cannot find ironwood nor mithril anywhere. I will try bringing Zephyra though, maybe it will help. Thanks!
(Edit: it did not work. Even her wind wall ability didn't seem to do anything. Oh well. Thanks anyway.)
Mostly because I enjoy the dungeon crawling element. I have multiple characters where I haven't even become mayor yet and managed to farm legendary tier tools, gear and over 5m cash. I set someone to purchase 100 of each dungeon at the start, including rebel redoubts, bandit den/forts, goblin caves and crypts. Mainly because I wanna get the initial lira meetup to get access to the elven kingdom, but my 3 grove completions didn't yield any lira events yet. So I'm farming dungeons until I get a grove with her event. Then I'll progress. And having to contend with a lich that has 2000hp isn't easy lmao. Especially now that I'm getting spider lair and goblin strongholds sometimes in magical events in dungeons.
Re: Ironwood etc, I was getting it as a slow trickle via manor upgrades. With a forge you can mostly ladder your way up through them.
But the strategy element was more important. Getting her into the open so I could land stun and blinds made a big difference.
Also, per the other comment, are you pushing your gear quality up to epic? You can use cheap materials for the upgrade pieces, and it adds quite an edge.