Diseased by blood

You shroud yourself with a thick fog of disease which infects and corrodes all who come into contact with you. Whenever a non-undead or construct creature hits you with a melee weapon attack, they must make a Constitution saving throw. On a failure, the creature takes 1d6 necrotic damage and becomes Poisoned for the duration and takes half as much damage and is not poisoned on a successful saving throw. While a creature is poisoned this way, they take 1d6 necrotic damage at the start of each of its turns. A creature can repeat its saving throw against this spell at the end of each of its turns, ending its effects on success.

At Higher Levels: When you cast this spell using a spell slot of 2nd level or higher, the damage increases by 1d6 for each slot level above 1st.