SRD:Amulet of the Planes
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Amulet of the Planes: This device usually appears to be a black circular amulet, although any character looking closely at it sees a dark, moving swirl of color. The amulet allows its wearer to utilize plane shift. However, this is a difficult item to master. The user must make a DC 15 Intelligence check in order to get the amulet to take her to the plane (and the specific location on that plane) that she wants. If she fails, the amulet transports her and all those traveling with her to a random location on that plane (01–60 on d%) or to a random plane (61–100).