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.
NM-Mint Foil - $9.30
Lightly Played Foil - $8.80
Moderately Played Foil - $8.30
Heavily Played Foil - $7.40
Damaged Foil - $6.00
NM-Mint Foil Non English - $9.30
Lightly Played Foil Non English - $8.80
Moderately Played Foil Non English - $8.30
Heavily Played Foil Non English - $7.40
Damaged Foil Non English - $6.00