How The Heck Do I Beat Big Boss Mech-dm666?

Seriously, this boss frickin haunts me man.

I can always get him to about ~10k health, but his regen is SO POWERFUL.

It takes like 5 minutes to get him down to 10k health, but as soon as I do that, I can never get him past that. He always regens to like 15k hp before I can get him past that mark, without fail each time.

I don't know if my build is just not working against him, or what, but holy crap I should be able to get him at least past the 10k mark.

Although, It's probably a build issue considering I haven't really made a specific build, more like threw a bunch of crap together that works for me.

 

This is sad please use a wynndata link next time
https://wynndata.tk/s/ct3dnr
or use brass brand dagger it works too