Air-cutting blade

You summon a longsword that is infused with air magics. It has the reach property and once before the spell ends you can forgo one of your attacks to release a cutting wave. A line of cutting wind 15 feet long and 5 feet wide emanates from you in a direction you choose. Each creature in the line must make a dexterity saving throw. A creature takes 2d8 slashing damage on a failed save or half as much on a successful one

Duration: 3 attacks or up to 1 minute.