Skull Watch is a 4th level ritual, which wardes an area against intruders. [OG:50] You enchant a skull to watch over an area and alert you when something intrudes. The skull uses your Perception modifier with a +5 bonus. It cannot hear or smell, and it never considers you an intruder. In addition, you can designate any number of other individuals as nonintruders. When you perform the ritual, you can also designate one or more categories of creatures that the skull will ignore. You can define these categories by obvious physical characteristics (such as height, weight, or body shape), creature type (such as humanoid), creature race (such as hill giant), or obvious equipment (such as a creature carrying a shield with a flame emblazoned upon it).