Orphan of Kos: Bloodborne | First Playthrough
Augur of Ebrietas is a good item to be used at his back in order for you to open up a visceral attack chance. Keep doing this on his first phase. The attacks that leave him vulnerable to Augur of Ebrietas are his jumping attacks, the sprinting attack (dodge to your right/his left twice) and the spinning weapon attack (as long as you stay on his left)
Staying on his left would be a good strategy for all of his phases. I tried to stay on his left so that I can use Augur of Ebrietas on his back (he has slow turn rate)
As for his second phase, just wait for the right time to attack. Being impatient in this phase would kill you. When he screams, turn off your lock-on so you can see the lightning. Being in water helps you a lot as the area is much bigger than the coast allowing you to be mobile also. -- Watch live at / hope_talledo