Storm Bolt

Str 13, Bash, Power Attack, base attack bonus +4

You can declare use of Storm Bolt before taking a full attack action with a ranged bludgeoning weapon. For the successful attack of your choice, roll damage normally, although the foe applies it as nonlethal damage. Also, the foe struck by your attack must make a Fortitude save (DC 10 + the damage rolled) or be stunned for 1 round. A stunned character can't act, loses any Dexterity bonus to AC, and takes a −2 penalty to AC. You can use Storm Bolt only once per round and no more than once per character level per day. When you use Storm Bolt, you forfeit any bonus or extra attacks granted by other feats or abilities (such as Manyshot or haste). Constructs, oozes, plants, undead, incorporeal creatures, and creatures immune to critical hits cannot be stunned.