Zurai said:Shadow Creature template from the Manual of the Planes (I think; it's either that or the Planar Handbook) is a very nice template for what I think you're looking for. It grants total concealment in any condition less than full daylight, plane shift to the plane of Shadows, extra speed, and some other goodies. It's the Dark template on steroids, basically (or, more precisely, the Dark template is a nerfed version of Shadow Creature).
Shadow Creature is in MotP and also Lords of Madness (the latter has the 3.5e update rules incorporated). It's one of my favorite templates ever. Speed boost, flavorful powers, and total concealment in anything less than full daylight -- love at first sight.Zurai said:Shadow Creature template from the Manual of the Planes (I think; it's either that or the Planar Handbook)
moritheil said:Shadow and Dark both come to mind for me as well, but I disagree with the assessment that Dark is weak. Dark gives HiPS, which alone is arguably worth a +1 LA. The rest of the stuff (darkvision, cold resist 10, etc.) is just a bonus. IIRC, there are some circumstances where you explicitly want Hide in Plain Sight.
I don't recall Shadow working in full darkness, either, which is inconvenient when you face creatures that can see in the dark (more common at high levels.)