Travelers of Sigil and the Lower Planes take care to avoid razorvine, a creeping plant named for its prickly stems and cutting leaves. While razorvine is normally a mere environmental nuisance or deterrent, razorvine that absorbs the blood of a vampiric passerby can awaken into a terror known as a razorvine blight.

Razorvine blights lay ambushes on well-traveled paths by standing still to appear as ordinary razorvine. When unassuming travelers pass by the seemingly inanimate plant, the blight strikes, revealing its twisted, humanlike form and lashing out with razor-sharp vines to feed its bloodlust.

While razorvine blights are usually dangerous, in Sigil they sometimes mimic the behaviors of the city's other inhabitants—for better or worse. At least one blight, known as Patch, spreads copies of itself across the city, creating a spy network of copies with mysterious goals.