Darkness Energy is a Reverse Holofoil variant card from the Power Keepers set, designated as card #87. As a Rare rarity card, it plays a crucial role in enhancing Darkness-type Pokémon's attacks and is valued at approximately $2.78 in the current market. Collectors appreciate its unique holographic design and its strategic importance in gameplay, contributing to its consistent demand among enthusiasts of the Pokémon Trading Card Game.