Nicol Bolas, God-Pharaoh

• WWizards of the Coast2017-07-14
  Official Ruling
  If the card has in its mana cost, you must choose 0 as the value of X when casting it without paying its mana cost.
• WWizards of the Coast2017-07-14
  Official Ruling
  In a multiplayer game, if a player leaves the game, all cards that player owns leave as well. If you leave the game, any spell or permanent cards you control from Nicol Bolas's first ability are exiled.
• WWizards of the Coast2017-07-14
  Official Ruling
  Casting the card exiled with Nicol Bolas's first ability follows the normal timing rules for casting that card. For example, if the card is a creature card, you can cast that card only during your main phase while the stack is empty.
• WWizards of the Coast2017-07-14
  Official Ruling
  While resolving Nicol Bolas's second ability, each opponent chooses which cards to exile from their hand. Any opponent with two or fewer cards exiles their entire hand.
• WWizards of the Coast2017-07-14
  Official Ruling
  The cards exiled by Nicol Bolas's first and second abilities are exiled face up.
• WWizards of the Coast2017-07-14
  Official Ruling
  You may cast the nonland card exiled by Nicol Bolas's first ability that turn even if Nicol Bolas is no longer on the battlefield or under your control.
• WWizards of the Coast2017-07-14
  Official Ruling
  If you don't cast the card exiled by Nicol Bolas's first ability that turn, it will remain exiled.
• WWizards of the Coast2017-07-14
  Official Ruling
  If you cast a card "without paying its mana cost," you can't choose to cast it for any alternative costs, such as emerge costs. You can, however, pay additional costs. If the card has any mandatory additional costs, such as that of Tormenting Voice, you must pay those to cast the card.

Rulings via Scryfall