Resting in a small chest set on a pedestal kept in a room populated with various artifacts lay two spheres that could fit both hands. One, glowing a brilliant blue-white, as a flame. The other darker than the blackest night.
God of Strength in the Night, Hiding your Numbers, and The Silent Kill.
Animals have parasites and diseases, so do plants, there are even bacteria that cann dissolve oil spills or plastic or what have you - why couldn't there be a disease living off magic - a magic item could be infected, losing power and speading the plague to other equipment it contacts, while a magic user would slowly lose his powers and contaminate all he works with or casts a spell at...