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 - $0.25
Lightly Played - $0.24
Moderately Played - $0.19
Heavily Played - $0.15
Damaged - $0.10
Near Mint Non-English - $0.25
Lightly Played Non-English - $0.24
Moderately Played Non-English - $0.19
Heavily Played Non-English - $0.15
Damaged Non-English - $0.10
Foil Prices
Near Mint Foil - $0.50
Lightly Played Foil - $0.25
Moderately Played Foil - $0.25
Heavily Played Foil - $0.25
Damaged Foil - $0.25
Near Mint Foil Non-English - $0.50
Lightly Played Foil Non-English - $0.25
Moderately Played Foil Non-English - $0.25
Heavily Played Foil Non-English - $0.25
Damaged Foil Non-English - $0.25