The Crystal Shard

At the beginning of your upkeep, if you both
own and control The Dark Crystal, and two
creatures named Jen, the Last Survivor, and
Kira, the Last Survivor, exile The Crystal Shard
and The Dark Crystal, then mend them into the
Crystal of Truth.
Ever since the Gelfing rebellion, the Skeksis have
forged many false shards with the intention of inciting
doubt and confusion, however, once the note of the
Mystics was played, the true shard was found.