This is a set of carved marble-like white stone blocks, from four to eight in number. The blocks are set up in sequence surrounding the area to be locked. A command word activates the wards, emanating invisible walls that prevent portals and gates of any kind from opening within their boundaries. Spells involving planar travel are likewise disabled as if by a zone of respite, though nothing prevents creatures from physically entering the warded area. Each block is carved with two numbers, and is about one-foot wide on each side. The first tells the user where in the sequence of wards to activate it, and the second is the number of blocks in the set. Blocks from one set do not work with the blocks of another set, and if someone attempts to use blocks from different sets, the magic is drained from all sets involved. The placement of the blocks determines the overall shape and area of the ward; they can be arranged up to 60 yards apart, in any pattern desired. The wall extends 60 yards above and below ground while arcing over to create a dome.

Speaking the deactivation command while in the warded area dispels the wards permanently.The wards also dissipate and fail a month after activation. Once dispelled, the blocks are no longer magical.

Caster Level: 15th; Prerequisite: Craft Wondrous Item, seal portal, zone of respite; Market Price: 10,000 gp; Weight: 2 lb. per block

Adapted from the Planescape Campaign Setting on Planewalker.com