With PFMW active and something to protect from level drain (Amulet of Power) you can actually yawn while the dragon is attacking you.
If he remembers to Wing Buffet you just come back and laugh at his face.
There is also a possibility that he uses Remove Magic so either you have SI:Abj on or just recast PFMW while running around. The second option is better IMO because SI:Abj also prevents you from casting PFMW.
You could have tried also the feeble drooling attack: Lower Resistance x2 (or 3x), Greater Malison, Feeblemind.
