The Reveal Glass is a key item only for the Pokémon Black 2 and Pokémon White 2 Versions. After that the player transfer his/her Landorus from the Pokémon Dream Radar to the game and bring him in his Therian Forme to the Abundant Shrine the player will receive the Reveal Glass which can change the form of Tornadus, Thundurus, and Landorus into their Incarnate Forme to their Therian Forme and can switch back in their Therian Forme to their Incarnate Forme.
This item can be received in X and Y by bringing either Tornadus, Thunderus, or Landorus to Reflecting Cave. Near the exit closest to Shalour City a scientist will give the player the Reveal Glass if the player shows her Tornadus, Thunderus, or Landorus. The reveal glass can be used to change them from their Incarnate form to their Therian form and vice versa.