What it does
Flying means a creature can only be blocked by other creatures with flying or reach. A flyer can still block anything—grounded creatures included—so it's purely an evasion ability on offense, not a restriction on what it can stop.
The most common mistake is thinking flyers can only block other flyers; they can block any attacker. Also note reach (not just flying) lets a creature block flyers, so don't assume your aerial attacker is unblockable just because the opponent has no flyers. Removing flying via an effect, or giving a blocker reach, can throw off attack math.
In Commander, flying is one of the most reliable evasion tools for connecting with commander damage (21 from a single commander) and for chipping down multiple opponents, since ground stalls are common across crowded four-player boards.













