X-Balls (エクスボール Ekusu Bōru) are a type of special medicine that allow Earth Land Mages to use their Magic in Edolas.
X-Balls are small red pills stored in a small bottle. They were used in Edolas by the Fairy Tail Mages. Once eaten, they enable the user to retain the ability of generating Magic Power, typically used by Earth Land Mages, even when travelling to a dimension like Edolas, where this isn't normally possible. Mystogan was the first one seen possessing these pills.