Shadow is an evasion ability with its own self-contained blocking restriction. A creature with shadow can only be blocked by other creatures that also have shadow, regardless of what other abilities the blocking creature has (CR 702.28b).
Flying grants the ability to block creatures with flying or reach, and forces non-flying, non-reach creatures to be unable to block it (CR 702.9b). However, flying says nothing about shadow — the two abilities operate on completely separate, independent tracking systems.
The key point is that shadow's restriction is not about 'being in the air' — it is a separate plane of existence mechanic. A flying creature without shadow cannot intercept a shadow creature any more than a ground creature can. Only a creature that itself has shadow (or in some edge cases, a creature whose rules text explicitly overrides shadow) can block a shadow creature.
Example: Your opponent attacks with Dauthi Slayer (shadow). You have Serra Angel (flying, vigilance). Even though Serra Angel has flying, it cannot be declared as a blocker for Dauthi Slayer because Serra Angel does not have shadow (CR 702.28b).
So to block a shadow creature, your only standard option is to control a creature that also has shadow. Flying, reach, trample, or any other common keyword will not help you here.
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.