Sonic Resonance - EX

When you hit a creature within 30 feet of you using a weapon in the sonic category, the sonic energy continues to resonate within that creature, giving it the flat-footed condition for 1 round. If you hit multiple creatures at the same time (such as with an automatic, blast, or explode weapon), only the creature nearest to you or to the center of the explosion (your choice if multiple creatures are equidistant) is affected.