Impetuous Sunchaser

• WWizards of the Coast2014-02-01
  Official Ruling
  You choose which player or planeswalker Impetuous Sunchaser attacks.
• WWizards of the Coast2014-02-01
  Official Ruling
  Impetuous Sunchaser attacks only if it's able to do so as the declare attackers step begins. If, at that time, it's tapped or affected by a spell or ability that says it can't attack, then it doesn't attack. If there's a cost associated with having it attack, you're not forced to pay that cost. If that cost isn't paid, Impetuous Sunchaser won't attack.

Rulings via Scryfall