Ugin's Insight

• WOTC Official Reminder Textofficial rules
  Scry — Look at the top N cards of your library, then put any number of them on the bottom of your library and the rest on top in any order.

• WWizards of the Coast2015-08-25
  Official Ruling
  Use the highest mana value among permanents you control as Ugin's Insight resolves to determine how many cards you scry.
• WWizards of the Coast2015-08-25
  Official Ruling
  If X is 0, you won't scry at all. Any abilities that trigger whenever you scry won't trigger.

Rulings via Scryfall