Surveil

Surveil is a keyword action that allows a player to look at a certain number of cards from the top of their library and put them in the graveyard or back on top in any order. It was introduced in Guilds of Ravnica for House Dimir of Ravnica. Surveil was reused sparingly in Modern Horizons 2.

Description
The instruction to surveil always includes a number, such as surveil 2 on Deadly Visit. Look at that many cards from the top of your library. From those cards, put as many cards as you like back on top of your library in any order. Put the rest into your graveyard. Surveil helps you set up better draws for the future. Even if all the cards you looked at end up in the graveyard, you're that much closer to what you need.

Surveil is very reminiscent of the scry ability, the difference being putting cards into your graveyard instead of putting them on the bottom of your library. The graveyard is a much readier resource, but be careful of decking yourself - many a Dimir deck in GRN Draft found itself unable to win before running out of cards.

Rulings

 * Some spells that instruct you to surveil require targets. You can't cast a spell without choosing legal targets. If all of those targets become illegal, the spell doesn't resolve and you won't surveil.
 * When you surveil, you may put all the cards you look at back on top of your library, you may put all of those cards into your graveyard, or you may put some of those cards on top and the rest of them into your graveyard.
 * You perform the actions stated on a card in sequence. For some spells and abilities, you'll surveil last. For others, you'll surveil and then perform other actions.
 * An ability that triggers "whenever you surveil" triggers after you're done surveilling, even if you have fewer cards in your library than the number of cards you're instructed to surveil. It even triggers if you have no cards in your library.

Cards that interact with surveil

 * Blood Operative
 * Darkblade Agent
 * Dimir Spybug
 * Disinformation Campaign
 * Enhanced Surveillance
 * Thoughtbound Phantasm
 * Whispering Snitch