Text (10+errata): 2/3, Flying. ; Creatures can't attack you unless their controller pays {2} for each creature he or she controls that's attacking you. [Oracle 2009/07/08]
The cost is paid as attackers are declared. [D'Angelo 2007/02/04]
If you have more than one of these in play, the cost is cumulative. [Legions FAQ 2003/01/23]