Whenever you cast a blue spell, Gravelgill Duo gets +1/+1 until end of turn.
Whenever you cast a black spell, Gravelgill Duo gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)
Near Mint - $0.30
Near Mint Non-English - $0.30
Lightly Played - $0.30
Lightly Played Non-English - $0.30
Played - $0.20
Played Non-English - $0.20
Heavily Played - $0.20
Heavily Played Non-English - $0.20
Damaged - $0.20
Damaged Non-English - $0.20
Foil Prices
Near Mint Foil - $1.00
Near Mint Foil Non-English - $1.00
Lightly Played Foil - $0.90
Lightly Played Foil Non-English - $0.90
Played Foil - $0.70
Played Foil Non-English - $0.70
Heavily Played Foil - $0.60
Heavily Played Foil Non-English - $0.60
Damaged Foil - $0.50
Damaged Foil Non-English - $0.50