First Referenced:
Our Final Acts (Part 3)
The Mind-Silencer is a device, similar to a bomb that when detonated, kills large numbers of sentient life forms. Its exact action is unknown, but is expected to directly attack the minds of victims, rather than causing them physical damage. As a result, physical armor is ineffective as a defensive measure.
When detonated by The Black-eyed Army in the battle of the Capital Temple, The mind-silencer killed approximately half a million members of the volunteer assault force seeking to secure the shield generator installations.