SRD:Horseshoes of a Zephyr
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Horseshoes of a Zephyr: These four iron shoes are affixed like normal horseshoes. They allow a horse to travel without actually touching the ground. The horse must still run above (always around 4 inches above) a roughly horizontal surface. This means that nonsolid or unstable surfaces can be crossed, and that movement is possible without leaving tracks on any sort of ground. The horse moves at its normal base land speed. All four shoes must be worn by the same animal for the magic to be effective.