Return of Xoriat
Schemas are the magic of Eberron in recorded form. Dating back to the time of the Giants, schemas have been used to pass magical knowledge through the generations. An individual schema might be a few sigils carved into a stone tablet, or an elaborate scripted presentation on the torso of a warforged titan.
In most cases, an individual schema represents a specific magical building block. These blocks can be combined into magical patterns, storing power ranging from simple cantrips to world-shaking destruction. A House Cannith magewright might use a simple pattern to quickly create hundreds of continual flame stones for use in street lamps, even as agents of the Emerald Claw seek to build a pattern that can replicate the destruction of Cyre.