Thundering

A thundering weapon creates a cacophonous roar like thunder whenever it strikes a target with a successful critical hit. The sonic energy does not harm the wielder. A thundering weapon deals an extra 1d8 points of sonic damage on a successful critical hit. If the weapon's critical multiplier is ×3, add an extra 2d8 points of sonic damage instead, and if the multiplier is ×4, add an extra 3d8 points of sonic damage. Subjects dealt critical hits by a thundering weapon must make a successful DC 14 Fortitude save or be deafened permanently.