A peculiar stone that makes certain species of Pokémon evolve. It is as dark as dark can be. Can be used to evolve Murkrow into Honchkrow, Misdreavus to Mismagius, Lampent to Chandelure and Doublade to Aegislash.
The Enigma Stone makes Latias and Latios appear in front of the Museum in Pewter City. You will need to take the Enigma Stone to Steven at the Pewter City Museum once you have handed over the stone. Latias or Latios will appear in front of the museum.