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 - $3.10
Lightly Played Foil - $2.80
Moderately Played Foil - $2.50
Heavily Played Foil - $2.20
Damaged Foil - $1.60
NM-Mint Foil Non English - $3.10
Lightly Played Foil Non English - $2.80
Moderately Played Foil Non English - $2.50
Heavily Played Foil Non English - $2.20
Damaged Foil Non English - $1.60