Mordenkainen's Lost Notebook
4-level Transmutation
Your touch corrupts a weapon. Where once it gleamed, it now grows dull and pitted with a rust-like patina which temporarily covers it. For the duration, when a living creature is struck by the corrupted weapon, it is afflicted with filth fever. A raging fever sweeps through the creature’s body. The creature has disadvantage on Strength checks, Strength saving throws, and attack rolls that use Strength. At the end of each of the target’s turns, it must make a Constitution saving throw. After failing three of these saving throws, the disease’s effects last for the duration, and the creature stops making these saves. After succeeding on three of these saving throws, the creature recovers from the disease, and the spell ends. Since this spell induces a natural disease in its target, any effect that removes a disease or otherwise ameliorates a disease’s effects apply to it.