The Light is usable by clicking the tab with "Light" written on it, it is right to the Monitor. It lights up the room, similar to Curtain Lamp. It will still use up power, even if the phone call is going. To use it again, you must open your Monitor, go to Laundry and charge the power (Hold, dont press).
Can ward off Waluigi if he's in the blind spot.
Every time you use the light, you have to generate the power in the Laundry,
it also takes time to do it, so use the light hen you know Waluigi is standing in the blind spot.
Wario could be in the room with the player and could result in a jumpscare while charging the light in the Laundry.