A shockwave inducer is a powerful and ancient protoss weapon, most likely pre-dating the Aeon of Strife. When activated, the inducer 'melds' with its user, dark liquid metal covering the torso and left arm. It changes shape every few second, with lights akin to stars flashing from the depths of the liquid. It has only been observed used by a protoss.
In addition to giving the user the ability to cast psionic shockwaves (hence the name), the inducer also carries a personality program, the function of which is to make the user more confident, bloodthirsty, etc. The nature of the user's personality will seemingly determine the extent of this however (e.g. an egocentric individual will become more delusional, believing himself to be a god for instance, than a modest person). This program is so refined that the device basically has a personality of its own (practically a form of artificial intelligence). The user's resilience to attack is also strengthened by the device.
Should the inducer take enough damage, it will drip off the user, form seven puddles of liquid metal, each solidifying into a separate piece ready for re-assembly. This process is traumatic for the user however, and will render him/her in a coma.