Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature gets +1/+1, has reach, and can block creatures with shadow as though they didn't have shadow. (Creatures with reach can block creatures with flying.)
If the enchanted creature has shadow, it won’t be able to block any creatures (not even those with shadow).
The enchanted creature can block creatures with shadow and creatures without shadow.