How bad is her dungeon anyway? I really want her
Well her dungeon isn't too hard if you multi.
But if you solo the boss battle in particular is going to force you to have lots of specific things on your team to counter it.
Since she puts on a 500k shield for 5 turns, you gotta stall them out, and she does like 30k+ every turn (increasingly more damage as you get nearer to the 5th turn) and also does a 6 turn bind to two members on her 3rd turn.
If you're multi-ing, you'd easily have enough hp and also the bind does not target leaders so you can just leave the killing to your partner if you're taking the bind, hence why it's much easier if you multi.
It does make farming very slow for most teams.