The Proving Ground is an area outside the campus of Brakebills University where students go to practice spells not allowed in the school.
Andy Tucker, along with Sophie Carlson and Brian Lee, brought new students Audrey Flowers, Emily Marks, and Pat Masterson to the Proving Ground to see what kind of magic they were capable of casting. Igniting the candles surrounding the area, Tucker told them to impress him, and Masterson began by using a spell to create a balloon from Tucker's words. Flowers then used her lasso to pull the moon closer, impressing everyone. Carlson then attempted to perform A Prayer to Xiuhtecuhtli, but lost control of the spell and died.