Blade Barrier

You create a vertical wall of whirling, razor-sharp blades made of magical energy. The wall appears within range and lasts for the duration. You can make a straight wall up to 100' long, 20' high, and 5' thick, or a ringed wall up to 60' in diameter, 20' high, and 5' thick. The wall provides three-quarters cover to creatures behind it, and its space is difficult terrain.

When a creature enters the wall's area for the first time on a turn or starts its turn there, the creature must make a Dexterity saving throw. On a failed save, the creature takes 6d10 slashing damage. On a successful save, the creature takes half as much damage.