Text (SM+errata): 7/5, Flying. ; When ~this~ enters the battlefield, you may discard your hand and draw cards equal to the damage dealt to target opponent this turn. [Oracle 2009/07/08]
You target an opponent when the triggered ability is put on the stack. You pick whetehr to discard or draw when the ability resolves. [Shadowmoor FAQ 2008/04/21]
It counts all damage dealt to the opponent from all sources this turn as of when this resolves. Prevented damage doesn't count. Damage that didn't cause loss of life (as with Worship) does count. [Shadowmoor FAQ 2008/04/21]
