I think of him as a stronger version of Rennala, who I'd call the least fun demigod. Both spam magic and teleport around while summoning crap.
However, I'd argue the worst fight is the gank fight just before the final boss. It's the only one I'd never even think about trying without doing any summoning myself. I probably could win eventually, but I don't think there's a second of enjoynent to be found here.
As a primarily PvP player, the battle Royale was the best one for me. Especially since even when the arenas were just added, I never would get matched up in anything other than 1v1s.
Though I am still disappointed there was nothing like DS3 or DS2's multiplayer specific fights like the Mirror Knight or Half-Light.