Monster species aren't any different from any other opponent. It can have all the chitin plating and what things it wants, but if my character is an assassin with probably fairly good eyesight and awareness, then that isn't exactly going to be a problem. Just stab a weak point in the armor...or, or don't even try it, and just slip past.

I'll just have to disagree, to be honest. Maybe it's just because I don't really believe in things like Luck, and prefer things to be based purely on skill more or less. Some level of luck is needed for a good story, but it should be little things.

If you want to throw a wrench into someone plans, then there are tons of better ways to do it than some silly concept known as 'luck'. I'll wait for Ash's reply and more detail about it...but eh, I'm not getting my hopes up.