Via Diabolis, commonly called the Road of the Devil and known as Tariq el-Shaitan to Islamic Canaanites, was one of the minor Roads that kindred may choose to follow in Vampire:DA.
Being an purely destructive Road, Via Diabolis was not considered a path to be taken lightly; those who dared followed it indulged themselves with all manner of debauchery and destruction. Many were not really evil per say, so much as believing a virtuous un-life was a fruitless pursuit. Some, however, took the role of devil seriously, even calling themselves devils incarnate and servants of Satan.
The Baali in particular came to be associated with Via Diabolis, though ironically many older and more powerful Baali actually despised it. Most Baali actually followed the minor Via Hyron, the Road of Hives, which had been the traditional road for centuries. Those Baali who followed Via Diabolis and actually took their role as the devil's servents were frowned upon by their Elders and called "lesser Baali". Many misguided neonates unfortunately took to following Via Diabolis, creating a minor crisis in the clan as the elder Baali wished for their childer to not attract so much attention to themselves. They worried the clan would be hunted down en masse by those the lesser Baali had wronged.
This is a path from Dark Ages and becomes the Path of Sin in Masquerade.