A terrifying creature born from impossible contradictions, the cocatrice is the elemental of Plague, the gruesome combination of Dark and Air. The cocatrice is a hulking amalgamation of a toad, a rooster, and a dragon. Covered in pustules that release a seeping green gunk, cocatrices are probably the most repulsive of all elementals.
The main weapon of a cocatrice is not its terrifying size or disgusting appearance, but the infectious plague it spreads behind it. Anything the cocatrice touches, approaches, or even looks at directly becomes infected with a terrible disease.
Those infected are rapidly covered in green pustules as the infection spreads, killing them slowly and painfully as they drown in the pus released by their sickened lungs. It's not a nice way to die.
The infectious plague of the cocatrice is too volatile and dangerous to even attempt to be weaponized, but it is thought that sorcerers trying to use the sickness to kill their enemies created the first Black Plague.