5 Desnus, 4721
When exposed to intense sunlight, perhaps enhanced due to the stained glass, the corpselight's weakness to sunlight is heightened to the point of destroying it.
A will-o'-wisp that starves to death might rise as a cold, blue, glowing sphere of spongy wetness—a corpselight. A corpselight instinctively seeks out a host corpse to dwell within, as its physical form quickly deteriorates if not hidden within a dead creature.