Under moonlight Jack transforms into a werewolf, a large, powerful hybrid human/wolf with superhuman strength, speed, stamina, agility, reflexes, etc.; enhanced senses, including ultraviolet and infrared vision; and razor-sharp teeth and claws able to rend light metals. The werewolf is resistant to many forms of conventional injury and virtually impossible to kill; though he can be severely wounded, he recovers from non-fatal wounds ten times faster than a human would. He is vulnerable to magical attack as well as to assaults involving silver, due to its inherent mystical "purity." When last seen he had little control over his werewolf form, which was becoming more bestial and savage, and he likely has even less control under a full moon.Russell formerly had total control of his transformation and could trigger or reverse it at will. He could transform his entire body or an isolated portion and could judge people's mental states. Sunlight caused him minor irritation, and he felt an increased urge to transform during the full moon. It was unclear if he could control whether wounds he inflicted turned others into werewolves.