Once a creature has been blocked, that creature remains blocked and will deal and be dealt combat damage even if it gains or loses shadow or if the blocking creature gains or loses shadow.
2021-03-19
If an attacking creature has multiple evasion abilities, such as shadow and flying, a creature can block it only if that creature satisfies all of the appropriate evasion abilities.
2021-03-19
Multiple instances of shadow on the same creature are redundant.
2004-10-04
Can be used on a creature that is already tapped.
Shadow (This creature can block or be blocked by only creatures with shadow.)
You may choose not to untap this creature during your untap step.
Whenever this creature deals damage to an opponent, tap target creature. That creature doesn't untap during its controller's untap step for as long as this creature remains tapped.
