Walls of light are electrified entryways that are powered by whale oil, situated around Dunwall for the purposes of security and quarantine control. Normally, only the City Watch and tallboys are able to pass through unharmed, as they deactivate upon their approach. Anyone else attempting passage, including trying to Blink through, will be vaporized.
Walls of light work via two electric coils placed together on either side of an entry, as if to resemble a gate. Above these coils is a revolving device, possibly a sensor, that emits a blue light. When a hostile approaches, it will sound an alarm and glow red. It will let out a low-pitched signal when someone attuned to the wall passes through it.
Corvo Attano, with the help of rewire tools, can reconfigure walls of light to allow him passage. This has the added effect of causing guards to be detected as "unauthorized" users, disintegrating them instantly. The device can also be disabled by removing the whale oil tank that powers it. The second level of the Bend Time power also allows Corvo to pass through an active wall of light unharmed.
- Rats tend to avoid active walls of light, and if a guard or other hostile notices that a friendly Wall of Light has been reprogrammed, they will as well. However, if a guard hasn't witnessed someone being disintegrated by the wall, he may attempt to pass it, even if there are other guards throwing stones at it.
- Bullets, bottles, and other inanimate objects will also disintegrate when coming in contact with a wall of light.
- This includes whale oil tanks, meaning that when thrown into a wall of light, they will not explode as they would normally.
- If a corpse or unconscious body is thrown into the wall, it will also disintegrate.
- Walls of light drain some of their supply of whale oil every time they incinerate something, and after enough uses, they will shut off.
- Once guards notice that a wall has been reprogrammed, they will start throwing rocks at it to drain the wall's supply of whale oil.
- Corvo can also utilize thrown bottles, projectiles, and other objects to deplete a wall of light's whale oil.