Its fairly statted as a 5/5 flier for five, and it packs innate protection in Ward Two
Its card draw rather than milling or discard, but that just makes it that much more of a fit for a wheels theme
For example, you could attack with Aspiring Champion and use Brainstorm to put a powerful Demon like Lord of Change on top of your library, ensuring that Aspiring Champion will become exactly what you intend and provide the most powerful result
Clue tokens seem like a natural fit, since they interact with both halves of the card
It clearly is a pushed card given the easiness with which the Cascade decks can hit their little combo
Based on current market prices, Sol Ring is the most valuable card in Foundations Promos, worth around $ 1.37