Radioactive Mutant is the 2nd enemy to be fought in Chapter 2, Book 6. He has 18 hearts. For some person, this is consired to be a hard enemy despite not being a boss, due to his attacks. The name of one of his attacks, "Do a Barrel Throw" is an obvious reference to the famous meme "Do a Barrel Roll".
|Do a Barrel Throw||Burns Lex||The Mutant throws a barrel to Lex|
|Isotope-A-Dope||Petrifies Lex||The Mutant gets waste in the barrel and throws it to petrify Lex|
|Waste Dump||Curses & Plagues Tile||The Mutant dumps waste in the barrel to the tile grid that makes the tile curse and plague|