The Dancer of the Boreal Valley is somewhat similar to the Pontiff Sulyvahn fight. She uses eratic moves that must be constantly blocked or rolled through and leaves small openings for attack. Again a good fire shield will help here. The fight will begin when you move towards the altar after speaking with Emma and acquiring the basin of vows. Hug the Dancer’s left leg and rotate around her to your right, striking a blow here and there when you can. Roll through any attacks she might do and get in one or two hits and repeat. Look out for her grab. There is a sound that plays while she simultaneously dips here shoulders, signaling the you need to roll backward out of the way or be grabbed and one shotted. It isn’t hard to spot, just listen for the sound.
Be vary of any attack she does where she plunges anything into the ground. These signal AoEs and you will need to back away or take massive damage. Once she hits phase 2 she will pull a second sword from the ground and begin to whirlwind around the room. Back as far as you can away, and if you can get the timing down roll through the last spin and squeeze in a couple of attacks. If you aren’t so confident, simply wait for the whirlwind to end and then resume the strategy. The main difference now is that she will have more combos and combos that last many more hits, so you will have to roll and block more and many times if you get hit by the first or second swing in one of her combos you will be stun locked and perish in a firey ashen death. Don’t get greedy with your attacks, play defensively and you should come out ok. .
As found on Youtube