Activated abilities of creatures you control cost X less to activate, where X is Agatha of the Vile Cauldron's power. This effect can't reduce the mana in that cost to less than one mana.
4RG: Other creatures you control get +1/+1 and gain trample and haste until end of turn.
Near Mint - $0.90
Lightly Played - $0.80
Played - $0.70
Heavily Played - $0.60
Damaged - $0.50
Near Mint Non-English - $0.90
Lightly Played Non-English - $0.80
Played Non-English - $0.70
Heavily Played Non-English - $0.60
Damaged Non-English - $0.50
Foil Prices
Near Mint Foil - $1.60
Lightly Played Foil - $1.40
Played Foil - $1.10
Heavily Played Foil - $1.00
Damaged Foil - $0.80
Near Mint Foil Non-English - $1.60
Lightly Played Foil Non-English - $1.40
Played Foil Non-English - $1.10
Heavily Played Foil Non-English - $1.00
Damaged Foil Non-English - $0.80