Corruption

You point at a creature within range and utter unholy words. The targeted creature must make a Constitution saving throw, suffering 3D6 Necrotic damage or half as much on a successful saving throw. The corruption feels like the inside of the body is in a rapid and painful change! Failing the saving throw causes the pain to linger, causing 1D6 Necrotic damage at the start of the creatures turn. The afflicted creature can make another saving throw attempt. On a success, the spell ends. The Corruption lasts up to 1 minute.

At higher level. The starting and the lingering damage dice is increased by 1D6 for each spell slot used above 1st level spell slots.