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 - $6.80
Lightly Played Foil - $6.10
Moderately Played Foil - $5.50
Heavily Played Foil - $4.80
Damaged Foil - $3.40
NM-Mint Foil Non English - $6.80
Lightly Played Foil Non English - $6.10
Moderately Played Foil Non English - $5.50
Heavily Played Foil Non English - $4.80
Damaged Foil Non English - $3.40