Guardian of the abyss (Dark Souls 3)

Guys, there is 7 hours of play, ass blazing nepodetski, I can't kill this thing. 1 phase pass on easy, but with 2 phase starts pzdts. I can't even half the HP off. After 6 hours decided to call the phantom to pocatalico so to speak)))))), in the end, it can't even pass phase 1.
MMMMM, AND IT SMELLS LIKE YAK