Good luck. Immortal didn't give me a real problem but inquisitor did. If it's any consolation, if you have to ultimate the thing, the next ones were really easy, I did chapter 5 having the last three dragons to do and no real issue. Saved my free videos up and sent out my best battlers.
As a side not, I know sometimes if I get a tough one, I mix up the bash and magic. I've also had great luck on waiting a 1/2 hour or so and then speeding it up. Something just feels like it resets itself. Keep cycling any Adipps and metal you have. Since you have tons of food, feed you diamond or infinity up a level. That's worked for me twin the past. When those font work find some low level, good for nothing common and suit him up - my son has awesome, random luck with level 4's "that will never work, mom". I also have good luck with three color dragons. You'll get him soon!