Okay I just finished this fight after 2 hours of F5 and F8.
I started with 3 level 18 characters and one level 19 character, and ended with all characters at level 19.
Didn't know it was going to be that bad but it was too late to turn back by the time I was at the dragon so I had to resort to a lot of F5 and F8 again and again and again.
For me, I kept focusing on the summons; killed them over and over. Eventually after a dozen more summons or so, he stops summoning them. (Figured if I was able to keep him stunned early then I wouldn't have to worry about the summons at all)
To protect Astarte, I kept a Spider as close to the dragon as possible and resummoned whenever he died. It seems the dragon attacks only the closest target (if one is really close).
So after the struggle with the summons I started pounding the dragon with Boulder Bash. I F5'ed before casting it and F8'ed if he wasn't knocked down (none of my characters had Drain Willpower so I had to resort to that).
Then I got my two fighters in and started hitting it. Took about 15-20 rounds to kill him or something. I just kept doing the F5 and F8 boulder bash trick and he never got up. I really have a shitty party (this is from my first playthrough and I didn't create any new characters or respec so it was really a shitty build with no proper strategy whatsoever).
But hey he died in the end, though I didn't feel that triumphant as I would have if I finished it in 3 rounds like some of you guys here.
Hopefully I can get a better build next playthrough.
Last edited by Syraxius; 08/08/14 08:59 PM.