Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

I was wondering how this mechanic works and what is it based on.
Does it have something to do with the feat Deflect arrows?
If yes, the feat states that it allows the user to deflect the first ranged attack each round. I noticed that some mobs sometimes deflect more than arrow in each round. Is there something I am missing?

Maybe they have epic deflect arrows...

A combat round also consists of 6 seconds from the time of rolled initiative, so it is technically possible for you to attack a mob at the end of one combat round (which it deflects), your char has a few dodge animations and then you attack again at the start of the mobs next round (which it deflects). That or epic deflection. It's really dumb that mobs have that feat at all unless they are actually monks...

Do they have a shield ? I know arrows are sometimes deflected by those. Either way the specifics are entirely hard coded and impossible to know for sure, only extensive testing will tell you what's up.

I think I recall the game putting out some rather misleading messages, saying that a ranged attack was parried when it simply missed. Can you confirm that the parried attack exceeded the target's effective AC?

Actually Valefort and Thorns bring up good points. If a mob is carrying a shield and you roll below their AC to hit with a ranged weapon, the game will often utilise the shield-parry animation to block said attack. It is an animation only and not necessarily representing any separate mechanic other than failing to hit their AC score.

It's a naked guy. The Gibberling boss. And yes, I exceed his AC with the shot.

I will try to identify it a bit more precisely - but the same thing happened with fire giants...

Ah, the Gibberling. I had thought it did have deflect arrows, which certainly used to affect ranged touch too, such as Warlock blasts. I don't recall it countering two attacks in a round, but that may imply epic deflection.