Curtain of Light

Oracle Text

Cast this spell only during combat after blockers are declared.

Target unblocked attacking creature becomes blocked. (This spell works on creatures that can't be blocked.)

Draw a card.

Card Rulings

6/1/2005 An attacking unblocked creature exists from the time the defending player chooses not to block that creature until the combat phase ends. Curtain of Light doesn’t have any legal targets outside of the combat phase.
6/1/2005 Curtain of Light does trigger bushido abilities.
6/1/2005 Curtain of Light isn’t particularly effective against creatures with trample. Since the creature with trample has no blocker to assign damage to, all the damage will be assigned to the defending player.
9/20/2013 If a turn has multiple combat phases, this spell can be cast during any of them as long as it’s after the beginning of that phase’s Declare Blockers Step.