Fateseal

Fateseal is a keyword action similar to scry. The only difference between them is that when you scry, you affect your own library, and when you fateseal, you affect an opponent's library.

History
Fateseal was introduced in Future Sight, but was based on the mechanic of the Mirage card Sealed Fate. It has only been printed on two cards so far, Mesmeric Sliver and Spin into Myth. Fateseal is considered to be a very un-fun mechanic by R&D, and is not expected to show up again any time soon.

Precognition has the effective text of "At the beginning of your upkeep, fateseal 1", which was printed back in Tempest. "Fateseal" has become the most common nickname for the first ability of the planeswalker Jace the Mind Sculptor, though the ability is not exactly the same since it allows also you to scry - but distinct from both, it can be redirected.

Rulings

 * The fateseal action doesn't target. You choose which opponent to affect as part of performing the action.