When Chthonian Nightmare enters the battlefield, you get EEE (three energy counters).
Pay X E, Sacrifice a creature, Return Cthonian Nightmare to its owner's hand: Return target creature card with mana value X from your graveyard to the battlefield. Activate only as a sorcery.
Near Mint Foil - £3.20
Lightly Played Foil - £2.80
Moderately Played Foil - £2.30
Heavily Played Foil - £1.60
Damaged Foil - £1.00
Near Mint Foil Non English - £3.20
Lightly Played Foil Non English - £2.80
Moderately Played Foil Non English - £2.30
Heavily Played Foil Non English - £1.60
Damaged Foil Non English - £1.00