Modding Help Temporary swapping an NPCs spritesheet inside an event

Has anyone used the changeSprite <actor> <sprite> command before?
The wiki states: Change the actor's sprite to be from "Characters/<actor>_<sprite>". But it isn't exactly clear on what it does.
I'm trying to find a way to temporarily swap an NPCs sprite sheet during an event so if this would work or if anyone knows a good way to achieve that, please let me know