Rune Bar

Merchants often refer to rune bars as 'one in a thousand bars'. The term has arisen because, 99.9% of the time, rune bars are unremarkable. They are safe to store in chests, banks and inventories and you could leave them there for decades without something remarkable happening.

But there is always that one in a thousand. Nobody has worked out why, but - on occasion - a rune bar misbehaves. You might come back to a pile of rune bars and find that one ringleader has caused them to rearrange into a henge. Rune bars have been know to spontaneously combust, fire like a cannonball from a backpack or convert back to a rune bar after being made into gauntlets. It happens frequently enough that merchants will eye a rune bar with suspicion.