The Safety Rug is an object found in the basement area of the Mansion preceding the Caverns, specifically in close vicinity of the demon zone-marker next to the small Chapel. The rug's arcane weave incorporates a safety device, apparently symbolized by the red pentagram in the centre, hence standing on it protects us from the imminent attack of the axe-wielding Lopers, presaged by the pair of demolished doors on the floor.
Adam: There's some sort of arcane design woven into this. Rebecca: Very odd. Adam: What do you mean? Rebecca: I've not seen one of these for a while. The weave incorporates a safety device. Adam: So you mean you stand in it and it'll protect you from something. Any ideas from what? Rebecca: They're not coming in. We're safe for the moment. Adam: That might sound good to you but we can't stay here forever.