The Sheddletide, often simply called the Tide or the Drift, is the gradual change in the nature and degree of arcane magic present at any point on Eamon, thought to be caused by the slow and undulous movement of cosmic ley lines. These shifts in magical potential can lead to harmful imbalances. Magic in some areas ("slubs") can diminish or disappear, while in other areas ("gouts") it grows so chaotically overloaded that routine spellcasting becomes dangerous and unpredictable.
The Rites of Xanara, a key element of the ancient Pact of Tuduska, was the first successful effort to moderate the effects of the Tide in localized areas, preventing the chaotic peaks and magic-nullifying troughs that had long bedeviled the world's mages. The rites continue to be performed through much of Addar to this day by practitioners called sheddlemancers, though the slubbing and gouting of the Tide still affects wild and uninhabited regions. It's thought that mages outside the Tuduskan tradition (as in the lands of the Ilvithri or the distant Orashta) likely have their own unique methods for handling the effects of the Tide.
Rifts can be influenced by the Sheddletide, but it doesn't cause them. Rifts tend to form through the movements of entire regions of the Material Planes through interplanar space, while variations in arcane magic (like the Tide) arise from the interactions of forces within Eamon's own plane.
