A Basic Pokemon Card of type Psychic with the title Mew and 50 HP of rarity Promo from the set Wizards Black Star Promos and the flavor text: So rare that it is still said to be a mirage by many experts. Only a few people have seen it worldwide. It has the attack Psywave with the cost Psychic, the energy cost 1 and the damage of 10 with the description: Does 10 damage times the number of Energy cards attached to the Defending Pokemon. It has the attack Devolution Beam with the cost Psychic, Psychic, the energy cost 2 with the description: Choose an evolved Pokemon (your own or your opponent's). Return the highest Stage Evolution card on that Pokemon to its player's hand. That Pokemon is no longer Asleep, Confused, Paralyzed, or Poisoned, or anything else that might be the result of an attack (just as if you had evolved it). It has weakness against Psychic 2. 
Mew