...the inhabitants of the dead city had, no doubt, some elaborate and beautiful name for them, but we just call them Vomiters. Victims of some disease--probably synthetic, definitely magical--they still appear on occasion, looking ill and looking pitiful, they stagger and moan and cough and reach out their hopeless hands and then hopelessly open their hopeless hellmouths, and out comes almost anything. Always a beast, always terrible--two in ten seconds, during the worst fits. Roll d100 + 5 and consult the corresponding page in the monster manual--or any other method you prefer.
They are, for all that, ordinary and capable of being killed by ordinary means--and will welcome it.