Adula's Moonblade

You conjure a cold magic greatsword and deliver a sweeping blow. Make a single melee spell attack targeting each creature within 10 feet of you. On a hit, a target takes 2d10 + your spellcasting ability modifier slashing damage.
A blade-like projectile of frost is then launched from the greatsword in a 20-foot-long, 15-foot-wide line. Each creature must make a Constitution saving throw. On a failed save, a creature takes 1d10 cold damage and is slowed until the end of your next turn. On a successful save, it takes half as much damage and isn't slowed.
At Higher Levels.
When you cast this spell using a spell slot of 6th level or higher, the damage of the greatsword and the projectile both increase by 1d10.