If the Pokemon 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 Pokemon Darkness Energy is attached to, unless it's D or has Dark in its name. Darkness Energy provides D Energy. (Doesn't count as a basic Energy card.)
Near Mint - $10.10
Lightly Played - $8.60
Moderately Played - $7.10
Heavily Played - $2.60
Damaged - $1.10
Near Mint Reverse Holofoil - $23.60
Lightly Played Reverse Holofoil - $20.00
Moderately Played Reverse Holofoil - $16.50
Heavily Played Reverse Holofoil - $5.90
Damaged Reverse Holofoil - $2.40