I haven't beat nightmare yet, but this is the deck I am using. The lack of completion is very much a matter of playtime and not deck power as I took quite a long break. It's been my favorite since I started having some sense about the game. If you want to use the AA12 over a breach loaded shotgun, find a card to drop for Quick Kill. Otherwise you will deadass just run out of ammo. I REALLY like down in front for solo Q, but if you are in a pre-made you could likely drop this card. Pick a card of your choice to replace it. If you don't like Cross Trainers, take a movement card of your choice. Though I DO NOT recommend Run Like Hell as you will be taking residual damage with this build. Marathon Runner is really underrated, but I just can't find room for it in this deck. I myself play this with Walker / Karlee / Mom depending, but it works with anyone except Jim really. If someone you are playing with has Money Grubbers, you could switch this with Copper Scavenger as well. Those 2 cards together will allow you to get both team bonuses every single round if you aren't completely depleted on health and other resources. I've been experimenting with a build that have a few "Pill" cards added, but this is not that and so far this has been more successful and consistent, even if the Pills variant has a tighter clutch factor.
Make your own modifications if you'd like, but this is what I use. Let me know what you think :)
