Aggravated Damage
Aggravated damage is not merely physical injury — it is a poisoning, an infection of the Kindred body by a harmful spirit or essence. The wound carries something of its source with it, and that essence resists the body's attempts to expel it. Those who look closely at the wounds of an affected Kindred can glimpse that essence still present within them — for example the glow of embers or a shimmer of sunlight.
The most common sources are fire and sunlight, whose essence is fundamentally hostile to the undead body. Other supernatural effects can also cause it, notably the black vitae poison of Protean — Horrid Aspect.
Effect
While a Kindred carries aggravated damage they heal at only 1 HP per night, regardless of Blood Potency. The poisoning does not leave them until they have fully healed — only once all damage is gone can the body finally push out the hostile essence.