Read the Runes

Oracle Text

Draw X cards. For each card drawn this way, discard a card unless you sacrifice a permanent.

Card Rulings

10/4/2004 You are never forced to sacrifice any permanents. You can choose to discard your entire hand if your hand is smaller than the number of cards you are required to discard.
10/4/2004 You draw the cards, then sacrifice any permanents you want to sacrifice, then discard the required number of card from your hand. There is no chance to play any cards in between these actions.