Quicksilver Amulet
Artifact
, 
: You may put a creature card from your hand onto the battlefield.
Those who examine the amulet too closely have been known to become part of its ornate carvings.
Brad Rigney
Magic 2012 (M12)
• #214Rulings
You don't pay any costs of that creature card, including additional costs.
(wotc • 2011-09-22)
Putting the card onto the battlefield is optional. When the ability resolves, you can choose not to.
(wotc • 2007-05-01)
Any 'X' in the creature's cost is treated as zero.
(wotc • 2004-10-04)
Rulings
You don't pay any costs of that creature card, including additional costs.
(wotc • 2011-09-22)
Putting the card onto the battlefield is optional. When the ability resolves, you can choose not to.
(wotc • 2007-05-01)
Any 'X' in the creature's cost is treated as zero.
(wotc • 2004-10-04)