How high is your strength stat? Are you inflicting a reasonable amount of damage through regular attacks? If so then junction 100 thundaga spells to your elemental attack.

This is the guy that counter-attacks with a whip/homing missile attack right? So for everytime you attack him, draw curaga from him (or one of his two floating segments) Don't attack him unless you can survive his counter attacks.

And it probabley goes without saying... but cast haste and shell on everyone