Oreskos Explorer

Oracle Text

When Oreskos Explorer enters the battlefield, search your library for up to X Plains cards, where X is the number of players who control more lands than you. Reveal those cards, put them into your hand, then shuffle your library.

Card Rulings

11/4/2015 The value of X is determined as Oreskos Explorer’s triggered ability resolves.
11/4/2015 If no player controls more lands than you do, you’ll still search and shuffle your library, although you can’t find any cards.