Darkness Energy (Expedition Base Set 158)

Rules

If the Pokémon Darkness Energy is attached to does damage with an attack (after applying Weakness and Resistance), the attack does 10 more damage. At the end of every turn, put 1 damage counter on the Pokémon Darkness Energy is attached to, unless it's Darkness or has Dark in its name. Darkness Energy provides Darkness Energy. (Doesn't count as a basic Energy card.)