Mystic Plaque is the third of the plaques, the one used to open the door leading into The Dragon's Lair. It was in possession of one of the Fiamma Nera cultists. Since the other two plaques were found in Floating Islands, it is possible that the third came from there as well, the cultist may have picked it up along the way and decided to keep it so no one could disturb Marco Bartoli's transformation in the Dragon's Lair. Lara Croft battled the cultists, took the third plaque, opened the doors and went on to defeat Marco Bartoli in his Dragon form.