Is that a save you make at every succesfull blow he lands ?
The reason I wondered was because I never saw any "daan: save *number*"
in the dialogue-box, although i did survive several of his blows without getting eaten alive ...
My eventual tactic was to simply cast PfMW, walk up to him, whack him with celestial fury and finally construct a device around him, that made one drop of water fall on his stunned head every second ( been tested and proven )..
By the time he could move again, he was afraid of water .. so I went to the underdark, leaving him alone in a city a few miles under the ocean