You may choose not to untap Amber Prison during your untap step. {4}, {T}: Tap target artifact, creature, or land. That permanent doesn't untap during its controller's untap step for as long as Amber Prison remains tapped.
Near Mint - $500
Lightly Played - $400
Moderately Played - $400
Heavily Played - $300
Damaged - $300
Near Mint Spanish - $500
Lightly Played Spanish - $400
Moderately Played Spanish - $400
Heavily Played Spanish - $300
Damaged Spanish - $300