Veil of Birds 
Enchantment
When an opponent casts a spell, if this permanent is an enchantment, it becomes a 1/1 Bird creature with flying.
Legality
standardNOT LEGALpioneerNOT LEGALmodernNOT LEGALlegacyLEGALvintageLEGALcommanderLEGAL
Enchantment
When an opponent casts a spell, if this permanent is an enchantment, it becomes a 1/1 Bird creature with flying.