Forbidden Knowledge

As a child, you somehow got your hands on a lurid, forbidden text written by a now-forgotten Blood Lord of ages past. You studied the details within intently, learning much about extraplanar undead from beyond this reality, and you developed a strange, almost macabre way of thinking because of this book’s influence. Anytime you would roll a Knowledge (planes) check, you may roll a Knowledge (history) or Knowledge (religion) check instead.