Bah, just do away with the way too variable damage fail condition. Every time any AI is adjusted, the devs have to go in and monitor every "protect" quest to make sure it's still on par with the intended difficulty. Just change the mechanics of that fight so that the impact of AI changes is limited. Don't start the fight until the players enter the actual arena and adjust the dragon hp down if necessary to compensate. In this way you lower the "failure window" from say 4 minutes (time to get from the shrine to the bottom) down to 15 seconds (time to get from the dragon arena entrance to the fight). By lowering the amount of time the dragon actually takes damage without players nearby, you lower the impact of AI changes that can wildly change the nature of the fight.
Kaarloe - Degenerate Matter - Argonnessen
Well I thought they changed it on elite spent about an hour trying to get a completion no luck...
Argo: Hilmir - Purkilius - Jinu - Vignir