Windreader Sphinx | Magic: The Gathering
Formats Windreader Sphinx is Legal in
Official Oracle Text for Windreader Sphinx
Whenever a creature with flying attacks, you may draw a card.
Official Rulings for Windreader Sphinx
7/1/2013 : Windreader Sphinx’s ability will trigger when it itself attacks.
7/1/2013 : The creature must have flying when declared as an attacking creature in order for Windreader Sphinx’s ability to trigger. For example, attacking with Trained Condor (a creature with flying and “Whenever Trained Condor attacks, another target creature you control gains flying until end of turn.”) and a creature without flying will cause the ability to trigger only once.