Shadow is an evasion ability that works independently from flying. A creature with shadow can only be blocked by creatures that also have shadow, and a creature without shadow can only be blocked by creatures without shadow (CR 702.27b). This restriction is completely separate from the flying/reach interaction.
Reach (CR 702.17a) allows a creature to block creatures with flying, overcoming the flying evasion ability. However, reach does nothing about shadow — it only addresses flying. Since the attacker has both flying and shadow, a potential blocker must independently satisfy both evasion restrictions.
To legally block a creature with both flying and shadow, the blocking creature would need to have shadow (to satisfy CR 702.27b) AND either flying or reach (to satisfy CR 702.9b). A creature with only reach satisfies the flying requirement but fails the shadow requirement, so it cannot block.
Example: Your opponent attacks with a 2/2 that has both flying and shadow. You control a 3/4 with reach. Even though your reach creature can normally block flyers, it cannot block this attacker because it lacks shadow. The attack goes through unblocked.
This is determined during the declare blockers step (CR 509.1b), where the game checks that each chosen blocker can legally block the attacker it is assigned to — all evasion abilities must be simultaneously satisfied.
Unofficial fan resource — not affiliated with or endorsed by Wizards of the Coast. Answers are AI-generated estimates grounded in the Comprehensive Rules and are not a substitute for an official judge. Verify anything match-critical.