Overseer Music Box

The Overseer Music Box is a device used by Warfare Overseers of the Abbey of the Everyman, which, when activated, prevents the use of any supernatural abilities within range, and can send out a sound-wave barrier to keep Corvo Attano away. Daud and his assassins are also susceptible to its effects.

As such, the protagonist is required to use his ranged and melee weaponry to combat Overseers who use them. The music box can also harm the protagonist by firing Windblast-like waves that push him backward, deal heavy damage and negate magical powers.

Corvo first discovers the device in the workshop located in the Back Yard of the Office of the High Overseer, where it is described in a note written by High Artificer Bartholomew and called "Holger's Device". According to the studies of the Abbey of the Everyman, the box produces "mathematically pure" notes, which act on the theory that there are hidden waves throughout the natural world.

In an audiograph recorded by the High Artificer, the concern is raised over whether or not the mechanism and its effects are themselves magic. However, this issue is not addressed by any other members of the Abbey.

Construction
Music boxes are built in secret locations around the Empire of the Isles by certain Overseers. The materials and processes used to create the boxes are concealed from all Overseers except those directly involved in the process to prevent heretics from building the devices themselves. The boxes are not built until they are required, then they are sent directly to the location that requested one. This process is lengthy, and some Overseers can be heard complaining about it, while others defend the procedure as necessary to prevent heresy.

Strategy
Overseers carrying this music box can be especially deadly. In addition to having their faces shielded by masks, those who carry the box can use it to protect themselves from strikes to the chest. The box's great range, ability to block damage, and the protagonist's hampered ability to flee without his powers make music box Overseers priority targets during combat.

A good strategy to kill an Overseer with a music box is to fire an incendiary bolt at his legs, as Overseers move slowly when carrying a music box and are easy targets. Grenades, explosive bullets, and sleep darts are also effective. They are vulnerable from the rear so attacking them from behind is a good tactic. If taking the low chaos approach, always make sure to get rid of Overseers with music boxes first. Their music can stop the protagonist mid-Blink and can cancel Possession and Dark Vision. Bend Time will also be affected, though Stop Time will not.

Trivia

 * Even though it is implied that bone charms, which usually emit some warmth, turn cold and useless when in the vicinity of the music,  the protagonist's charms will continue to work normally.
 * Two City Watch Officers can be overheard in the Estate District discussing a rumor that a group of Overseers declared a woman a witch because she lost her voice just as Overseers passed by with a music box.
 * Music boxes can also break glass and cause whale oil tanks to explode.
 * Overseers occasionally play the music box even when not alerted. This does no damage but still negates supernatural abilities when close by.
 * One concept image shows what appears to be a stilt-less tallboy wielding a music box.
 * After the events of Dishonored, the music boxes were put in storage and not used again until Dishonored: The Corroded Man, in 1851. When they were removed from storage, many were out of tune.
 * Music boxes with a new design can be seen in Dishonored 2 set in 1852, but are never seen used by Overseers.
 * A pair of Overseers can be heard discussing their lack of music boxes, saying that they are waiting for more to arrive.
 * The Overseers are stated to have used the music boxes against Delilah Copperspoon and her coven, but this happened offscreen. They failed because the boxes were ineffective against Kirin Jindosh's Clockwork Soldiers.