Siege Dragon 
Creature — Dragon
Flying When this creature enters, destroy all Walls your opponents control. Whenever this creature attacks, if defending player controls no Walls, it deals 2 damage to each creature without flying that player controls.
Legality
standardNOT LEGALpioneerLEGALmodernLEGALlegacyLEGALvintageLEGALcommanderLEGAL