I was thinking about a high school/college smart science kid who essentially becomes a Man-Thing corollary after an unfortunate encounter with some toxic waste in a swamp. Permanent transformation. Super tough and very strong with a plant-based suffocation attack, but no longer intelligent and unable to generally communicate. May have some emotive/empath power to help with communicating. I'm not sure if the origin story character would hit PL 5. I could build him lower and make up the difference in powers, but not sure if that would make them overly powerful compared to the others.