I gave my cleric 50 in all stats and he had Scather. I'm level 14 with 350 HP. I cast Stone Skin but could still only manage around 400 damage which puts him in orange state. Even if I could survive, there doesn't seem to be a way to deal enough damage before Cuthbert arrives.
He's trying to take him out in 3 rounds. Summoning distractions may help his survive ability, but it will lower his DPR. I know that in the extra content patch you can fight Iuz again, without a time limit, later on. But there are four of him. I don't know if you'll be able to take him out in 3 rounds with just one character.
Not with a lvl 14 Cleric I couldn't. Not enough dps. Even if I could scather counter every attack I reckon he'd still have HP when Cuthbert showed up. Now a Fighter or Barbarian on the other hand...
Don't know about soloing him, but with a standard party I was able to trip him with an enlarged monk, when Cuthbert showed up it was like he didn't see him laying on the floor so I had more time to whale on him.
What allignement are you? In order to fully benefit of Scather you have to be CG. Also, you should have Power Attack feat taken and set to maximum ( having the Scather you don't care about the "to hit" penalty) which ads to he damage. And you actually WANT to be hit, in order for the Scather to retaliate, so don't try to defend or summon meatshield ( I actually strip of shield and armour in this fight! ). Don't remember if at this stage of the game you have access at a Haste potion, but that would greatly help! Of course, wanting to stay on your feet, lots and lots and lots of stoneskins. Hope it helps.
I was soloing with a CG cleric using scather with full power attack but only had one stone skin memorised. I calculated that I couldn't have done enough retaliation damage even if I survived for the amount of time needed. What's Iuz's HP? Like 750? I only managed 420 at best.
