Stone Mask

Story
Originally known only to a vampiric cult hidden within the Aztec empire, the stone masks were designed by Cars as an initial attempt to give his race the ability to withstand sunlight. However, they were "only" powerful enough to turn humans into vampires. Sometime during the mid-to-late 19th century, the mask was excavated by humans and later the subject of research by Jonathan Joestar, who was unable to understand its purpose and was only able to come up with speculative theories. These theories attracted the morbid curiosity of Dio Brando, who believed it to have been an execution item that he could attempt to use on Jonathan, and after testing it on another human, realizes that it transforms them into vampires. During his struggle with the Joestars, Dio use a hidden blade to stab George Joestar I in order to activate the Stone Mask become a vampire. This would start a long grudge between him and the Joestars.

Abilities
The mask is triggered when it is touched by human blood. It will then extend tendrils of stone from its edges, piercing the wearer's skull and brain. The tendrils are meant to precisely find and trigger certain points in the brain in a fashion similar to acupuncture, and from thereon release the wearer's potential strength. This surge will give the wearer vampiric powers and superhuman strength, but also render the body effectively "dead" and unable to contain life, such as direct sunlight or hamon.