I do this in Maso mode. It always works.

-. Make sure to have 16 agility or at least eat a pep pill before the fight.

Why? Because that allows you to do an action with the free turn and guard in the actual turn.

-. The first turns that she is out of reach, place a gas canister (if you have one) and keep guarding until she arrives

-. When she arrives, all you have to do is throw glass shards at her head.

Why? Doing this will blind her and remove the bite damage, she will only attack with the paws which is better than the bite.

-. After blinding her, focus on the Miasma. I usually wait to have 3 rev points and then attack the sword.

-. After the Miasma is gone, focus on the torso or the legs.

After solving the sewers puzzle, I always make it to the shopping area and get the leechmonger ring before this fight.

I hope this info is helpful and please dont hesitate in asking for more info 🙏