Found it on youtube.
What you need:
- Face Puncher - does melee damage when you shoot it
- A powerful gun you want to shoot a lot of but are usually concerned about ammo running out. I like scourge rocket launcher, ion rocket launcher, and vladoff snipers.
- ammo stealing artifact - every time you melee you get more ammo for you and your allies
- I am also using the new Zane class mod from the DLC. “Seein’ Dead”. So worth it.
Spec into the capstone of the doppleganger tree so that your clone copies your gun. Also, for this, I like making my clone last as long as possible. So, skill duration is good. And action skill cooldown is also great. I also use sentinel now for the xtra damage output. And generally I boost damage output in the rest of my skill tree.
When entering a fight, switch to face puncher and start your doppleganger. As long he is shooting an enemy he’s now getting you ammo for your currently equipped gun. Now you switch to whatever gun you want to shoot a lot and start firing.
I noticed my power potential jumped dramatically from what I was doing before (generally using an Atlas Q system, and speed). I was more comfortable on Mayhem 1 or 2. Now I am very comfortable on Mayhem 4 on TVHM. I have to run more tests, but I definitely feel like Zane is finally growing into his power.
That said, we’d all appreciate Gearbox making sure all his skills work and perhaps some buffs still, so that more builds feel viable. For instance, most of his other legendary class mods are very weak.
Face puncher wikia entry
Just one of the youtube videos about it: