Satyr Piper

• WWizards of the Coast2013-09-15
  Official Ruling
  If multiple attacking creatures must be blocked, the defending player must assign blockers in such a way that the greatest number of those attacking creatures are blocked.
• WWizards of the Coast2013-09-15
  Official Ruling
  During the declare blockers step, the defending player must assign at least one blocker to each creature that must be blocked if that player controls any creatures that could block it.

Rulings via Scryfall