The Villain That Never Was

Unfortunately, the sequel I proposed for Tales of the TMNT #36 was rejected. I had planned on introducing a new villain who I thought would go down well and suit the TMNT universe, but unless I can work him into another story for the powers-that-be, then this is probably the only time you'll see him (although I do have an idea for something creator owned that I'm thinking of working him into). Here's my initial scribble, and then Paul Harmon's incredible take...
His pre-Diamondback persona is actually there in #36...