Wolf belt

A wolf belt is a talisman used in the transformation of a human being into a wolf. It plays a role in Fool Moon.

Description
The belt transforms the person into a huge wolf-like beast by providing an anchor for a "spirit of bestial rage" from the Nevernever, which wraps itself around the human personality. The spirit would influence the wearer, suppress their conscience and control them more fully. The hexenwolf's personality, although initally protected from the transformation's effects by the presence of the talisman's spirit, will continually erode over time and be destroyed completely. The belt's use is very addictive. The enchantment is very powerful and without effective control, making it effectively evil. Harry Dresden activates it with the incantation: "lupus, luparo, luparoso".

Fool Moon
In Fool Moon, FBI Agent Phillip Denton and his three colleagues made a deal with some anonymous source for the belts. They originally planned to use the belts to take down Gentleman John Marcone and kill him. But the belts changed them so that they were subject to wild blood-lust and could not refrain from killing, causing the Lobo killings case. To explain any evidence, they made efforts to set up both the Streetwolves, a gang of lycanthropes, and Harley MacFinn, a loup-garou.

Dresden had taken a belt from agent Roger Harris, one of Denton's people. Harry's magic has been failiing him and lives are at stake and as a last resort he puts on the belt. He changes into a wolf instantly and takes on Agent Benn, debilitating her. Then he and Denton fight, both in wolf-form. Wearing the wolf belt changes Harry on the inside as well, and rapidly. He begins to lose himself. Just as Dresden is about to kill Denton, Susan Rodriguez pleads with him not to. He balks at first, then from deep within he realizes that he'll never be Harry again if he does.