Cloak of Shadow

This dark gray cloak appears to be made of diaphanous cloth that always seems to be fluttering slightly, as though in a breeze. When worn with the hood up, a cloak of shadow gives the wearer a +5 competence bonus on Hide checks in areas of shadowy illumination bus applies a -5 penalty in brightly lit areas. In addition, when the wearer is in complete darkness, he can become incorporeal once per day for up to 1 minute.
The cloak is actually a greater shadow, bound to the shape of a cloak by magic. Once per day, the wearer can command the shadow to come forth, and it does the wearer's bidding until slain, or until the wearer commands it to return to its cloak form. If the shadow is slain, it reverts to cloak form and can't be brought forth again for seven days (the cloak functions normally, but the shadow can't be activated during this time). If the cloak is destroyed, the shadow is destroyed forever. Should the wearer enter the Plane of Shadow, the greater shadow is free to act on its own-and may well attempt to slay its former master.
Strong conjuration; CL 15th; Craft Wondrous Item, summon monster VIII, ethereal jaunt; Price 75,000 gp; Weight 1 lb.
Source: Planar Handbook