What does Power Critical do?

[AlwaysSummer Day]

Seriously? I never did figure out exactly what this feat does. It says

When using the selected weapon, the player gains a +4 bonus on the roll to confirm the threat for a critical hit.

as far as I know you roll within the crit range and you hit them with a crit barring crit immunity. Is there some sort of hidden mechanic that makes you roll again to confirm that the first 20 was real or something?

[Steve]

To score a critical hit, an attacker must first score a threat (usually a natural 20 on an attack roll) and then succeed on a critical roll (just like another attack roll).

http://nwn2.wikia.com/wiki/Critical_hit

Translation: the engine makes 2 roles (one for the attack; one for the crit to actually crit (if it doesn't, it is just normal non-crit damage).

[Rhifox]

DnD crits work by first rolling a 20 (or lower, if a wider crit range), then making a second roll to confirm the crit. The second roll only needs to beat the target's AC, it doesn't need to also hit the crit range.

Power Critical gives you a +4 bonus on the second roll.

[AlwaysSummer Day]

I hate when the game engine hides mechanics from players. . .

[mrm3ntalist]

I hate when the game engine hides mechanics from players. . .

Its not hidden. The AB roll and the confirm roll show in your log