Batarang (Sonic)

The Sonic Batarang sent out a high-pitched wailing sound, which attracted any inmate in earshot. As they got close, the Sonic Batarang could be detonated to incapacitate the inmate, provided that you upgraded them to the Sonic Shock Batarang. However, doing this creates interference that prevents any more Sonic Batarangs from being used for the remainder of the map.

If the Sonic Batarang was left only to attract potential targets and not used to shock them, a henchman would either step on it or shoot it.