Touch of Decay

Make a melee spell attack against a creature you can reach. On a hit, the target takes 3d10 necrotic damage and must make a Constitution saving throw. On failure, that creature is afflicted by decay. The condition lasts for one minute, or until that creature succeeds on the saving throw (repeated at the end of each of its turns).

Decay- A creature afflicted by decay is gripped by necromantic energies. While affected, the creature cannot be healed by means of spells or potions, instead being damaged for the amount of healing they would receive. Undead and constructs are immune to this effect.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the damage increases by 1d10 for each slot level above 3rd.