You may have up to 4 Basic Pokémon cards in your deck with Unown in their names
Unown [D]
40 HP
Pokémon Power
[Darkness]
Whenever a Pokémon damages 1 of your Pokémon, reduce that damage by 30 (after applying Weakness and Resistance). This power stops working if you have more than 1 Unown [D] in play. (This power works even if Unown [D] is Asleep, Confused, or Paralyzed.)