Abi-Dalzim's Horrid Wilting

You draw the moisture from every creature in a 30-foot cube centered on a point you choose within range. Each creature in that area must make a Constitution saving throw. Constructs and undead aren't affected, and plants and water elementals make this saving throw with disadvantage. A creature takes 10d8 necrotic damage on a failed save, or half as much damage on a successful one.