I beat him by using physical attacks from my party to damage him, and having the character I controlled act as a healer, reviving the dead.

Magick is pretty useless unless you can pierce reflect.

When he uses the pailing use only 1 character at a time to decrease the damage you take, and try to play keep away so he gets less spells in until the Pailing wares off. After the pailing falls, try and do quickening if possible.