This spell reveals all normal or magical portals within its area of effect. This includes doors, windows, magical gales, tunnel openings, teleportals, shifting walls, secret doors, openings concealed by illusions, and similar constructions. False or illusionary doors are excluded; there must be or have been some possibility of function as a method of entrance or egress. The caster does not gain any information about how a portal is used: locks, traps, method of operation, direction of operation (in the case of one-way doors), and similar information is not learned. However, if a portal itself is magical or if it is magically concealed, the caster has a 10% per level chance to determine what type of magic is involved. The spell is most useful for finding secret doors, shifting walls, and the like.
Notes: Very rare spell. (Updated from Polyhedron Magazine.)