Screwing around with the Bullet Sponges, decided to put the Skillcraft set on and see if it worked with Wretched Shadows - just to make sure. (It does.) Great!
Went to respec to my normal build. Then I got called away, and when I got back, I realized that A) I had forgotten to pause, and B) the Sponges were still screaming. First pic extremely related.
Quitting to the main menu was the fastest way to stop the DoTs.
What's happening here is:
Gamer triggers a DoT when C4SH deals crit damage.
The DoT is counted as Skill damage. Skillcraft makes Skill damage able to crit.
So now the DoT can crit, which triggers the DoT. That's literally the entire setup that's required to achieve incomprehensibly large damage numbers.
I tried shooting each of the dummies in the face once, and then started writing this post. Hopefully the screenshot of the results is attached properly.
From left: Bonnie and Clyde shotgun mode, Truck, Bonnie and Clyde AR mode, Shalashaska.
I would be shocked if this doesn't get patched very soon. Especially since the only thing that would be required is to make the Gamer effect not able to trigger itself.
Edit: I tried to use this on Bloomreaper, but I guess they're immune to the DoT. Too bad.