In NWN2, only creatures with 4 HD or less can be coup de graced and there is no fortitude save.
Coup de grace is a full-round action that allows an attacker to attempt a killing blow against a helpless opponent. A coup de grace can be administered with a melee weapon, or with a ranged weapon if the attacker is adjacent to the opponent.
An attacker delivering a coup de grace automatically scores a critical hit, after which the defender must make a Fortitude save (DC 10 + damage dealt) or die. Rogues also gain their extra sneak attack damage for this attack.
Literal Definition And PronounciationEdit
coup de grace(koo-de-gras)  - lit. a blow of mercy. a killing strike made out of mercy to end suffering/pain OR a decisive or ending blow
- In NWN, coup de grace did not provide a fortitude save and always ended in death.