Matter of AC?

[xXTaikunXx]

So here's my question: what's the reason, that xmas ice dragon can hit me while I'm 85ac, while he can't hit a friend of mine who has higher phys lvl.
We both have 30 str, 30 dex and lvl 110 so that can't be the reason.

Could anyone explain me what the important stats are so that he can't punch me in mah face? Does phys or mental lvl play a role here? I've already heard about this issue from other players aswell. Would be nice to know, what stat to lvl first, so they can't hit and blind me anymore. Hope somebody can tell me.