The most tenacious plant in the multiverse, razorvine — often referred to as the "kudzu of the planes" — is an icon of Sigil, and any illustrations of the city don't seem complete without the image of razorvine climbing the walls or wrapping itself around the wrought-iron work of the city. Indeed, much of the ironwork of Sigil is designed to mimic razorvine, both in appearance and in effect. However, it's hardly limited to that city; after all, a single cutting of the plant is enough to infest an entire town in mere weeks, and often has.
Outside Sigil, razorvine is most often found in the Lower Planes or Low Outlands. It's somewhat well-associated with Plague-Mort — where razorvine patches are often used to dispose of dying victims, and where the toughest cultivar is said to grow — and Ribcage — where a massive years-long project to clear the city of the weed was finally completed in Hashkar 126, after which extreme penalties were put into law against any who would bring even a single cutting into the city — but by far the city most well-known for razorvine beyond the Cage is Curst. Not only is the Gate to Carceri made out of nothing but razorvine, and not only are the walls covered in a variety that seems linked to the city itself, reaching up as needed to keep citizens from escaping over the walls, but the Cilenei vineyards are the only known source of heartwine, a sour wine somehow made from the plant. Though its true origins are lost to time, because of its common association with the lower planes razorvine is often thought to have originated there, likely either the Abyss or Carceri.
Razorvine is a clinging vine with glossy black, heart-shaped leaves with serrated edges that grow in dense clumps near the stem on short, wiry sprigs. Each leaf grows about an inch or two across, and though inedible to humanoids, are edible for certain grazing animals — Fhorge and quill are commonly found grazing on wild razorvine in the Lower Outlands. The plant will grow quickly across any surface, averaging a foot of growth a day, with some reports of up to six; it's been found in nearly every environment. Thankfully, razorvine cannot take root in open water, and extreme temperatures, such as those found in deserts or tundras, prevent its growth. Much as kudzu, the quick growth of razorvine will quickly kill other plants through light deprivation, growing over top of them so thick that no sunlight can pass through.
Though the leaves of razorvine look dangerous, they're harmless to the touch. The true danger of razorvine is the stiff, triangular stem, its edges blade-sharp; sharp enough to slice flesh, cloth, and even uncured leather with a touch. So dangerous is razorvine, it's occasionally purposefully cultivated beneath the windows or across the walls of manorhouses; though not an especially attractive plant, it's an excellent deterrent for thieves. On incidental contact with razorvine, a creature takes 1d6 points of slashing damage. If pushed into or falling onto an especially large patch, a creature takes 3d6 points of slashing damage, plus 1d6 for every round they remain within it afterwards.
The vine, when alive, is highly resistant to fire and herbicide, with physical clearing the only reliable way of removing it. Not that cutting it is easy. Each individual root system can produce anywhere from 2 to 20 separate vines, each twisting on one another so much that identifying the actual source is incredibly difficult. It's also naturally quite tough and difficult to cut through, and the sharp edges tend to wear gardening tools down more quickly than other plants. Razorvine has hardness 5 and 60 hp per five feet of depth, with a break DC of 26. If clearing from a wall or object, treat each two foot wide section of the growth as its own patch with 2 hp. Further, razorvine has fire resistance 10 and immunity to poison.
Thankfully, when cut, razorvine quickly turns brittle, within ten to fifteen minutes losing all sharpness and good for little more than kindling. Before reaching that point, though, it can still be quite the danger; in fact, using a quick razorvine cutting as a makeshift garrote or lash is a common trick amongst thugs or assassins in Lower cities or Sigil. A razorvine whip or garrote deals an additional 1d4 damage on a successful hit, and increases the critical hit modifier of the weapon by 1.
- Dungeon #150 - Savage Tide: Prince of Demons, pg.69
- Harbinger House, pg.44
- In the Cage - A Guide to Sigil, pg.7
- Planar Handbook, pg.146
- Planescape Campaign Setting - Sigil and Beyond, pgs.35-36,59-60
- Planescape Monstrous Compendium Appendix II, pp.78-79
- Well of Worlds, pg.93