There are customs, then there is customising..
I stumbled across this reworking of the Sideshow Heath Ledger Joker
The artists appears to have added to base, and repainted the head sculpt taking it to another level. While i am not a fan of rooted hair, it does lend itself well to Joker.
For a moment i thought the artist had reworked the left and right arms. It appears the images have been flipped.
..and the flames appears to have been upgraded to light up, making them looks much better.
Update: The image does not appear to have been flipped, as the base looks correct. I guess the left and right arms have been worked on also.