Legendary difficulty seems to be almost impossible. I have tried with both a warrior and mage; neither of them have been able to get past the second beach.
A side note to Tumalu's advice. Instead of switching platforms during his laser eye attacks, just stay in the corner and attack him during both. This will allow you to combo the hits into major damage. He can't hit you from this location either.
Is it even possible to get 100% on dragon taming before your apprentice turns 18? I started doing the taming as soon as I could, and didn't stop until he turned 18. I wasn't able to max it.
Is the rogue's poison proficiency skill (the one with 25 ranks) bugging out for anyone else? I just had an attack with one of my rogues and the poison didn't apply.