True Wither

Necromantic energy washes over a creature of your choice that you can see within range, draining moisture and vitality from it. The target must make a Constitution saving throw. The target takes 15d10 necrotic and 5d10 cold damage on a failed save, or half as much damage on a successful one. This spell has no effect on constructs.

If you target a plant creature or a magical plant, it makes the saving throw with disadvantage, and the spell deals maximum damage to it.

If a creature is reducet to 0 hit points with this spell it withers and dies