Ulysses was right when he said the Stonfeld Crypt isn't forgiving.

I know this place looks tough, but:

1) The monsters in a box are the hardest part. The regular enemies aren't that bad at all.
2) An extra level or 2 would have been very helpful (goes without saying)
3) At this point it's possible to get Tressa to join you; obviously a fourth set of hands (and a fourth body to take hits) would be very useful.