Did you beat him yet? You can actually cheese him to death with poison knives since he's vulnerable to them (takes about 15-17 poison knives and he'll be dead). If I wasn't so over leveled I would have definitely used that tactic when I fought him.
The only boss that gave me a really hard time out of all the chalice dungeon bosses was Amygdala in the defiled chalice. She's piss easy to beat by facing her back and hitting a charged attack. Unfortunately, 1 mistake and you're dead. Took me about an hour to beat her. Even Ebrietas in the Great Isz chalice didn't give me a problem although she's a much harder boss.
Honestly, having completed almost all of the chalice dungeons, I think they're a bit of a disappointment. Yes, you can farm some pretty good items and the bosses are way harder than the in game bosses but the dungeon layers become so tedious once you've familiarized yourself with them. I think it would have been better if they would have added like 5 or 6 areas to the game with the same difficulty and same chance of getting rare items rather than having the chalice dungeons themselves.