The hydravise is an Underdark offshoot of the greenvise (Monster Manual II, 120) that has adapted to feed off of living flesh to replace sunlight when it is deprived of nutrients. Its ferocity was well-noted by Underdark herbalists, who brought its seeds to the surface to sell them as guardians and weapons. A hydravise resembles a giant, purple, eight-headed Venus flytrap with vicious, cellulose-formed teeth that look like five-inch long thorns. Each of its eight heads release an acidic substance that is extremely potent and corrosive.