D&Dtools1

This transmutation makes a ranged weapon strike true against your favored enemies.
All rolls made to confirm critical hits by the weapon against favored enemies automatically succeed, so every threat is a critical hit.
The affected weapon also ignores any miss chance due to concealment whenever you fire at a favored enemy (unless the target has total concealment, in which case the normal miss chance applies).
If the ranged weapon or the projectile fired has any magical effect or property related to critical hits, this spell has no effect on it.