Devouring Plague

You afflict the target with a horrible plague of shadow. At the beginning of each or the affected creature's turns, it must make a Constitution saving throw or suffer 2d8 shadow damage, and their hit points are reduced by an amount equal to the damage taken. A creature that succeeds on the saving throw takes half damage and does not have their hit points reduced. Three consecutive saves ends the spell early. You regain hit points equal to half the damage dealt by this spell.

This spell induces a supernatural disease in its target, so any effect that removes a disease or otherwise ameliorates a disease's effects apply to it. Dispel magic has no effect.

At Higher Levels. When you cast this spell at 5th level or higher, the damage increases by 1d8 for each spell level above 4th.