"Veilstone Amulet" is a colorless artifact printed as a rare for the Magic the Gathering expansion set known as "Future Sight." This artifact has an ability that pretty much helps you protect your creatures for the time being. In a control deck that requires some creatures, Veilstone Amulet comes in very handy. In an aggressive deck which requires plenty of creatures, the Veilstone Amulet is most certain invaluable.
The converted mana cost for the Veilstone Amulet is three. You are going to need three mana of any color to cast the Veilstone Amulet. For what this Veilstone Amulet can grant you, three mana is a reasonable price. Keep in mind that the Veilstone Amulet is an artifact. It means that Veilstone Amulet is susceptible to anything and everything that affects artifacts. Spells such as "Akroma's Vengeance," "Planar Cleansing," and "Naturalize" could easily destroy the Veilstone Amulet.
What does the Veilstone Amulet do in the first place?
As long as Veilstone Amulet is on the battlefield, your creatures will have Shroud during the turn whenever you play a spell. If it is your turn, you can play planeswalkers, enchantments, artifacts, sorceries, and/or creatures. Any one of those spells will trigger the ability of the Veilstone Amulet. When it is not your turn, you can play an instant spell or a spell that has Flash. Doing so prevents your opponents from trying anything that targets your creatures.
The best thing is that you can still equip artifacts to your creatures. You can even put counters on your creatures. While Veilstone Amulet does grant Shroud, it mainly applies to your opponents. While your opponents cannot do anything directly to your creatures, you can still use enchantments and equipment artifacts on them. This is another reason that Veilstone Amulet is appealing.
In this respect, opponents cannot try stuff like "Lightning Bolt," "Incinerate," and so forth on your creatures if you had cast a spell with Veilstone Amulet being on the battlefield.
However, Veilstone Amulet itself can still be targeted. An opponent could simply play a spell such as "Disenchant" to get rid of the Veilstone Amulet. Also, an opponent could play a spell such as "Diabolic Edict" or "Chainer's Edict" which makes you sacrifice a creature. While Veilstone Amulet can protect your creatures against most spells, it does not protect them from everything. Even with Veilstone Amulet on the battlefield, an opponent could play spells such as "Wrath of God," "Damnation," or "Day of Judgment' which wipes out all creatures. Those spells affect all creatures. While this is a good card, Veilstone Amulet does have its vulnerabilities.