To attune Black Heart a potion brewed from the item's noxious emissions and the owner's own blood must be created. Creating this potion is a Great test of alchemy skill. Once prepared the owner must don the pendant and quaff the potion. This afflicts the owner with a Good potency disease, which inflicts Good damage each day for seven days. The victim may attempt to resist this disease effect once per day (a Great test of toughness required). Any success reduces the damage for the day to Average. Any form of healing applied to the owner negates the entire attunement process. If they survive the entire seven days Black Heart becomes fully attuned, and grants its new owner full understanding of its powers:
- Black Heart grants a Great resistance bonus to all forms of disease and poison, and reduces any damage received from these sources by two ranks.
- All healing effects applied to Black Heart's owner suffer a one rank penalty in effectiveness.
- Venom Touch - At will the wearer can inflict a poison attack doing Good damage to their victim by touch. The victim can reduce this damage to Average with a Good resistance check.
- Noxious Brew - The wearer can use the noxious emissions of the heart and a portion of their own blood to create three doses of Great strength poison (requires an Average test of Alchemy). This poison can be injected or ingested, and inflicts Good damage for four rounds (Great resistance check to reduce damage to Fair each round). Drawing the blood required to make this venom inflicts an Average wound on the wearer.
- Disease Cloud - The wearer can cause Black Heart to expel a cloud of noxious vapors in a 15 foot radius around themselves. This cloud infects anyone within the area of effect with a vitality-draining disease (Great resistance check per round of exposure to avoid). Once inflicted the disease drains one rank of vitality from the victim every six hours. The disease lasts seven days or until cured. Creatures slain by the vitality drain are permanently slain, their bodies reduced to dust. This power can be invoked once per day. The wearer is immune to the effects.