Scry is a mechanic unique to the Watcher.
Whenever you Scry, you will look at a certain number of cards on top of your draw pile. You then may choose to discard any number of them. 
Scry does not reshuffle your deck. If you have fewer cards in your draw pile than the Scry amount, the Scry applies to whatever is left in the draw pile.
Scrying displays top and bottom cards in order from left to right.
These cards have Scry. Numbers in parentheses are for upgraded version:
- Cut Through Fate: Scry 2(3) cards.
- Keep in mind that the leftmost card that is not chosen to be discarded will immediately be drawn after you confirm your discard choice.
- Just Lucky: Scry 1(2) card(s).
- Third Eye: Scry 3(5) cards.
- Foresight: At the start of your turn before you draw your cards, Scry 3(4) cards.
- This effectively allow you to discard a number of cards before it is drawn.
These cards have interaction with Scrying in general:
- Nirvana: After you Scry, gain Block.
- Weave: After you Scry, return from discard pile to your hand.
- If you Scry and choose to discard Weave, it will return to your hand after confirming your discard choices, effectively allow you to both discard it from the next draw and use it to attack an enemy.
- Golden Eye: Whenever you Scry, Scry 2 additional cards.
- Melange: Whenever you shuffle your draw pile, Scry 3.
- Before the Watcher was released, the blue card Reprogram used has its effect akin to Scry 4(5), albeit worded differently. It got reworked after the Watcher was released, as to make Scrying a unique mechanic of the Watcher.