When you level up, your spells are free this round.
The Sphinx is one of the advanced Heroes in Storybook Brawl.
This page is a stub, it will be expanded at some point. Probably.
Game Update History
Version 0.67.4, January 2022: Text changed from “Your shop sells an extra spell. When you level up, your spells are free this round.”
Version 0.65.10, December 2021: First introduced
List Of Heroes