Instead of making a new post ill ask here, how the heck are you supposed to kill him? I mean, I got him to human form, but then what happens? He takes out his bow, shots me for 190-220 dmg, then uses his fear skill or whatever and finishes me with one sword hit, so I'm basically getting 2-shotted here, am I bugged or what? ._. Or maybe I'm not 'supposed' to go there until I get higher lvl? I just dinged 13 and same shit happened.
It is a boss battle, so it is supposed to be hard. I am usually level 15-16 at that point, though, but still Amdusias does a lot of damage with his bow. Though it seems Amdusias has been made considerably stronger in the English version.
Note, though, that ranged damage can be reduced with higher dexterity. So if you have a Potion of Dexterity, it's time to drink that. Also, you should always have Potions of Greater Healing.
It is possible if you are a mage or ranger, to take cover behind a rock... then let your creature act as distraction while you shoot him with arrows/pelt him with magic blast or fireball.
For a warrior, you really should have a lot of vitality & strength at this point so you can kill him quickly. As always with bosses, Fatality skill is very useful.