Animus

"Animus" was Anna Ripley's pepperbox pistol, her second designed gun. This gun was a in some ways an improvement from Ripley's first design, Retort, as it has six barrels, and hence six shots before a reload. (Retort had a rotating chamber which could store only four charges at a time.) Not only were there multiple barrels, the gun was magically enchanted and dealt additional psychic damage to the target. When Animus jammed, it dealt 2d6 psychic damage to the wielder.

Percy gained possession of Animus after the death of Anna Ripley, and used it as one of his main weapons.

The gun was similar in design to Percy's pepperbox pistol "The List". However, it was thinner, longer, and more refined. The gun was a deep grey color with brass sections. It also had some whitestone built into it.

The demon of vengeance, Orthax, was bound to Ripley through Animus, much like he was to Percy through his pepperbox pistol "The List". The names of the people that Ripley sought vengeance against were inscribed on each of the barrels of Animus, just like on Percy's "The List". When Vox Machina encountered Ripley on Glintshore in, two of the barrels were already blank, with no names on them. The other four barrels had the following names on them:
 * Percival de Rolo
 * Oz Gruude
 * King Bertrand Dwendal
 * Richter Wells

After Ripley dealt the finishing blow on Percy, his name vanished from the barrel in a puff of black smoke.

When Keyleth severed Orthax's connection to Animus via her Greater Restoration spell, the remaining names on the barrels vanished in a flash of shadow. However, when Percy later attuned Animus to himself, the names were still on the gun and vanished again with a dark glow. It's possible this was an error made by Matthew Mercer.

Trivia

 * As revealed by Matthew Mercer during the Fireside Chat, the names on Animus (except for Percy and King Dwendal) were the four people who had worked alongside Ripley while she developed military technology for the Dwendalian Empire. They discovered her illegal human experimentation into arcane diseases, and the four of them turned her in to the crown. Ripley was scheduled for court-martial before she managed to use what little magic she had to escape prison and flee the Dwendalian Empire.
 * Based on the two blank barrels, it is apparent that Ripley had already acquired her vengeance on half of her former team before encountering Vox Machina on Glintshore. Ozwyn "Oz" Gruude and Richter Wells, along with King Dwendal, are the only survivors from Ripley's arrest.