When you cast this spell cast this spell, you must expend two hit die or else the spell fails.   You light your blood aflame, coating one hand in a diseased fire. While this spell is active, you can make a melee spell attack to attack with your burning appendage. This spell attack deals an amount of fire damage equal to the hit dice expended to cast this spell. Any creature hit by your burning appendage must also make a Constitution saving throw, on a failure taking 1d6 necrotic damage every turn until this spell ends. They may repeat this saving throw at the start of their turn, on a success ending the effect.