Drain Life (Homebrewed)

Choose up to five creatures in a 30-foot cube. They must make a Constitution saving throw equal to your spell DC or take 5d8 necrotic damage per minute, or half damage on a successful save. In combat, each target afflicted by this spell takes 1d4 damage at the beginning of each of their turns, or half (minimum of 1) damage on a successful save. The target may make additional Constitution saving throws at the end of each minute the spell targets them for. If damage taken this way reduces the target to 0 hit points, the target instantly dies.

When this spell is cast at 3rd level or higher, the spell can affect an additional two creatures of your choice per additional level of the spell slot used.