Zugzwang's Leftover Rock

Zugzwang's Leftover Rock
Group Collectible
Tradeable Yes
Refundable No
Limited Edition No
Description
This would be a plain, ordinary rock if only it didn't have Zugzwang's signature insignia proudly stamped on the side. Oh, and if it didn't exude magical residue like crazy!

This is obviously a powerful artifact used by the great Zugzwang, but what was it used for?
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