Dresden Files: Boston
Skills Affected: Fists
Natural Weapons: You have claws (or something similar) that are Weapon 1. This bonus stacks with any advantages due to Strength abilities or other powers or stunts that boost the damage of a Fists attack.
Venomous [-2]: Your claws are venomous, allowing you to create an advantage (Poisoned Aspect). In each subsequent exchange, the target must roll Endurance to defend against an attack from the poison equal to your Fists score. Once the target concedes or is take out (falling unconscious), the attacks stop. However, the damage is already done; without proper medical attention, a taken out victim will die soon (within a few hours, perhaps less), though not immediately.
Proper medical attention will remove the aspect and end the effect. This is an opposed roll – you can roll Fists (since that was the skill for the original attack) to set the difficulty to mitigate the poison.