[Balor]

UPDATE:

Having tested Mirror Shards, it appears that Shards spawned prior to 2.39 still seem to work.  However any and all Mirror Shards spawned in as of 2.39 by either shard picker or from treasure balls do not work work. At all.

UPDATE: 

So Ricky originally bought a mirror shard from a shop, likely a shard from before 2.38 at the latest if that.  That particular shard worked.  However upon placing shards in a shop and purchasing them no shards worked, and after purchasing a shard yesterday from the same shop Ricky did. That shard didn't work, so ignore anything I just posted above.