Specced out of the Blue Tree passive "Torgue Cross=Promotion" since it's increase in explosion size is more often killing yourself with the Flakker Shotgun manufactured by… well Torgue. F*CK YOU MR. TORGUE! MORE EXPLOSIONS MY ASS! Check the Blue Tree section for the details.
We take advantage of some gear-specific items in order to enhance our shields and provide the ability to self sustain to survive and deal high damage.
So the first thing that's required for the build is a Legendary Artifact called Deathless. The Deathless artifact reserves all but 1HP in return for 100% extra shields, as well as a 25% increase in shield recharge rate and a 20% reduction in shield recharge delay. A lot of our skill tree passives boost shields and give us bonuses on how low our health is, so it pairs up perfectly! All artifacts can have a prefix as well. None of them are required, but I personally prefer the "Snowdrift" prefix as it gives you +102% slide speed which is nice for travelling around a map quickly when you don't have a vehicle. For stats, I would look for Area of Effect, shock resistance, or anything else that looks good for you. Just to note, you can get a 29% resistance to shock here.
The Bloodletter is a legendary class mod that converts any HP healed or regenerated into shield healing/regeration. This is what enables you to survive. Any source of healing will restore your shields and thus keep you alive. The primary source of healing is coming from the Blue Tree passive "Vampyr" which heals you for 20% of your health every time your grenade does damage, which is then converted to 20% shields. You can look for whatever passive bonuses you want, but more or less it's not going to change how the build plays out much. Personally, I would try to get as much of a bonus on "Thin Red Line" as possible, as it converts health into shields, and since the Deathless reserves it all anyway, it's just a flat increase to shields with no downside. For the stat rolls on it, you can look for Splash damage, Area of Effect, Shotgun Damage, Grenade Damage, Shield Capacity, or whatever you feel like trying to get.
Now, honestly, you can use pretty much anything here. The higher the capacity, the better. There's no hard requirement to make the build work. However, the legendary Re-Router shield is my preference. When you are at full shields, the Re-Router empowers your next shot to deal 120% bonus damage by draining 50% of your shields and heals you for the damage dealt. This is another incredible source of healing with a specific weapon that I will go over soon. If you do enough damage, the 50% shields that you lose, just immediately go right back up to full and empower the next shot again. Look for an Improved Re-Router with Shock Resistance.
The Recurring prefix means that it not only splits into 2 grenades when you throw one out, but each of those 2 grenades also split into 3 more on contact with an enemy or any surface(MIRV-Tacular spawns the same amount of grenades so either can work)… meaning you have 6 sources of splash damage which not only means high damage, but also recovering grenades/ammo and healing. I'd look for one with either Shock, Corrosive or Radiation damage. Shock is nice to burn through enemy shields, Corrosive helps melt enemy armor, and Radiation is nice for big Area of Effect damage when you're surrounded by a ton of enemies.
Guns (pretty much just 1, but whatever)
The Flakker is a Legendary Torgue Shotgun that creates multiple explosions which cover a very large area in front of you. Again… explosions mean splash damage, means regenerating ammo and grenades. If your shot is empowered by your Re-Router shield, the Flakker is going to put you back to full shields almost instantly, which empowers the next shot again. Stack this with the kill skill buffs throughout the Passive Trees and watch Bosses, Anointed, Bad Ass, etc enemies' health just melt in front of your eyes. Look for a non-elemental version with the highest base damage and splash damage radius you can.
Since this build is mostly a close to mid-range combat fighter, there's a couple things that might help out against bosses that are far away such as Graveward or Katagawa Ball. Some shock/corrosive Lucian's Call, Rowan's Call, Cutsman, Crossroad, Infinity, just to name a few. Any high fire rate SMG or AR will help with enemies farther away that have shields and/or armor, but some flat physical damage guns are nice as well such as a Vicious Lyuda.
Fire in the Skag Den (Max). We're focusing on splash damage so it's just a little bonus.
Grizzled (Max). Since we're speccing out of Torgue Cross-Promotion, this is pretty much the only useful thing that's left. We'll pair this with Auto Bear later to pop in, pop out, and trigger our anoints as often as you'd like.
Means of Destruction (Max). A main piece of the build that generates ammo and grenades for you as you deal splash damage.
Pull the Holy Pin (Max). Nothing else is worth taking and this is just nice for some added grenade damage.
Auto Bear. With the change in the tree, we're taking a point out of Why Can't I Carry All These Grenades to put 1 here. All we're gonna do is pop Mech, and immediately jump out. This will trigger anoints on our gear and provide a turret that shoots enemies for us. Not super helpful, but much better than killing yourself all the time with Torgue Cross-Promotion
Vampyr (Max). A large reason why this build works at all. Any time an enemy is damaged from a grenade, you heal 20% of your health. This is nuts. This gets converted to shields.
Why Can't I Carry All These Grenades (2). More grenades. Not necessarily mandatory, but getting down the tree requires points put in and this is the best option, so win-win.
To the Last. Only need 1 more point to get to the bottom passive on the tree. Again this isn't mandatory for the build to work, but is just a nice little QoL to have. In the chance you do go down for FFYL, just throw grenades and you'll be back up in no time!
Short Fuse. Anytime you deal gun damage, you have a chance for a secondary explosion. Explosion means splash damage. Splash damage means regenerating ammo and grenades.
Armored Infantry (Max). We're going to have shields almost all the time, so it's just a straight boost to Gun Damage as well as Damage Reduction!
Thin Red Line (Max). This just further boosts our shields at no cost to life because of the Deathless Artifact.
Vladof Ingenuity (Max). Boosts shields, duh, and provides high shock resists. Shock damage is strong against shields, and since we have 1 HP, it's important we protect our shields where we can, so this is great to max.
Drowning in Brass (2). Nice buff, just need a couple points to get us down the tree.
Desperate Measures (Max). We're at 1HP all the time. So it's a permanent +50% boost to gun damage(pr more if your class mod boosts this skill).
Behind the Iron Curtain (2). Nice speed buffs for shields, though it's only helpful when you're not dealing or taking damage. Otherwise, you're regenerating shields all the time.
Phalanx Doctrine (2). Every kill you get boosts your shields and your gun damage for 30 seconds. The more you kill, the more damage you do and the more shields you have to survive!
You may be interested in pulling out of the Blue Tree a little to get down the Red Tree instead for Tenacious Defense. In theory it looks amazing, providing you an instant 40% shield recovery when it breaks, but because you're at 1HP, if your shield breaks, you're going down and the shield recovery won't matter. The only time it would work is if you took exactly enough damage to break your shields but not a single point more so that your 1HP keeps you alive. And that's not ever going to happen in this game with the gear we have.
Alright, there it is! Let me know your thoughts, if you find anything that works better for you, etc… post down in the comments! Thanks guys and gals!