Maybe this has been discussed so far but if not (potential spoiler in link)
 

https://mobile.twitter.com/CrmChsAlchemist/status/596141178426261505/photo/1

What is there to discuss?

It's the card art from the mix & match toyline. You see Leo there with Tigerclaw's torso, Splinter's leg, Shredder's arm, etc.

This is nothing.

Toy card back art. Literally nothing.

like the others have said its just a toy art for the mix and match line where you can mix and match parts onto different figures

http://i60.tinypic.com/2q3sle8.jpg