Windborn Muse | Magic: The Gathering
Formats Windborn Muse is Legal in
Official Oracle Text for Windborn Muse
Creatures can't attack you unless their controller pays for each creature he or she controls that's attacking you.
—Akroma, angelic avenger
Official Rulings for Windborn Muse
2/1/2007 : In the Two-Headed Giant format, you still only have to pay once per creature.
2/1/2014 : Unless some effect explicitly says otherwise, a creature that can't attack you can still attack a planeswalker you control.