Back from the Brink

• WWizards of the Coast2011-09-22
  Official Ruling
  If you exile a double-faced creature card this way, you'll pay the mana cost of the front face. The token will be a copy of the front face and it won't be able to transform.
• WWizards of the Coast2011-09-22
  Official Ruling
  Although you're paying the card's mana cost, you aren't casting that card. Abilities that reduce the cost to cast a creature spell won't apply, and additional costs to cast that creature can't be paid. Alternative costs that affect what it costs to cast a creature spell, such as evoke, can't.
• WWizards of the Coast2011-09-22
  Official Ruling
  Any "enters" abilities of the creature will trigger when the token enters. Any "as [this creature] enters" or "[this creature] enters with" abilities of the creature will also work.
• WWizards of the Coast2011-09-22
  Official Ruling
  If the exiled creature card has in its mana cost, X is considered to be zero.

Rulings via Scryfall