This isn't a dragon, its a wyvern. We all know that everything is as powerful as how hard it hits, casts, hitpoints, and level anyway so lets cut this god / dragon nonsense.
Verant made mobs like this very powerful for the sake of gameplay. I think its cool to have an ancient wyvern.
No one told anyone they had to kill anything, so people shouldn't criticize the difficulty of any mob.
Just the same I would reccommend bringing 3 full groups of 50+ to try to take this one out.