Mewtwo is one of the most sought-after Pokémon in Pokémon GO, and dedicated Trainers may find a truly exceptional specimen if they’re lucky enough to be invited to EX Raids. Mewtwo will return as the opponent of these special encounters, and the Psychic-type Pokémon will know the move Shadow Ball when caught—a move that Mewtwo can no longer learn in most ways. Plus, if you’re even luckier, the Mewtwo you encounter might also be a Shiny Mewtwo.

EX Raid Battles are only available to Trainers who receive an invitation to compete. You can become eligible to receive an EX Raid Pass when you win a Raid Battle at a qualifying Gym. You’ll be able to see which Gyms can host EX Raids through a handy tag when you look at the Gym details. EX Raid Passes will give you the date and time when you’ll be able to challenge Mewtwo, so mark your calendar and prepare your Pokémon for a difficult battle.