+7.5-15% Weak Spot Damage. Weakspot Kills also ignore Enemy Hit Mass.
Up to +5-20% Strength based on the charge time of your heavy attacks. Stacks 3 times.
+10% Critical Chance for every 0.2-0.35 second while aiming. Stacks 10 times. Discharges all stacks upon firing.
6-15% Strength bonus on your ranged attack for 3 seconds after cleaving through several enemies with your weapon's special attack.
This is the closest we're likely to get. This build uses the folding latrine shovel to kill everything short of a Chaos Spawn in a single overhand smack to the noggin.
MELEE
Both Thrust and Brutal Momentum are needed for this build, and are likely best-in-slot on all the ogryn shovels anyway. Combining these and the talent tree mean you can (with a decent stat roll) oneshot literally any normal enemy in the game with one folded heavy attack or a folded light. Notably, your folded lights kill Muties. Bear in mind the talent Batter (Inflict 4 Bleed Stacks on Heavy Attack) may have to be swapped for Crunch! (+40% Damage and Stagger on Fully Charged Heavy Attack) if your shovel doesn't have high enough Damage, First Target, and Penetration rolls. I think Batter is better if you can swing it for a few reasons:
While the damage potential is absolutely wild here, the choice of a XIX adds a complexity: It's hard to build up stacks of your keystone, Heavy Hitter, when the weapon's heavy attacks are single-target overheads. Those overheads give you a lot more versatility and reliability in killing elites and specials in dense crowds without needing to leave yourself vulnerable with a shovel fold, but gaining those stacks is challenging. Once we're at max stacks, combined with headshots to trigger Brutal Momentum's cleave, the light attacks destroy hordes easily. So, we solve this crowd control problem with:
RANGED
Not only is the Kickback an excellent crowd killer all by itself, it's special attacks count as heavy attacks. This means we use the Kickback like we normally would anyway, blasting down hallways and killing midrange specials and elites, but also to engage a fresh horde encounter: When you hear a horde coming, swap to your kickback and mash special attack into the crowd to kill a few grunts and very quickly build up to max stacks of Heavy Hitter. Then just swap back to the shovel, let the light attacks melt the horde for you, and your heavy and folded attacks turn any armoured fool who dares enter melee with you in a crumpled wad of paper. Since you're gonna be going out of your way to smack heretics with your gun anyway, taking Punishing Fire as a blessing will give a nice damage boost.
BLITZ, ABILITY, AURA, & KEYSTONE
Rock covers your only weakness of not having ranged special killing and is also never not funny.
Bull Charge is incredibly versatile, Bruiser gives it a wicked fast cooldown, and its modifiers make you even more survivable and boost your damage even further.
Bonebreaker's Aura and Heavy Hitter puts you over multiple breakpoints with your shovel, and Brutish Momentum is absolutely necessary on the Mk XIX.
This build should you absolutely shitting out obscene amounts of damage, with incredibly high Toughness regen. Not only can you solo Crusher hordes with ease, the only things that can do more damage to bosses than you in melee are Zealots running with either a Thunderhammer, Stealthshroud, or both.
The hitboxes on the folded overhead attacks are absolutely fucking enormous. Brutal Momentum will make your folded attacks reliably kill 4 enemies per swing instead of 1, and is capable of killing 4 closely-packed Maulers or Crushers. I reliably kill 2 at once at least a few times each run.
BREAKPOINTS
NORMAL HEAVY ATTACK:
FOLDED LIGHT ATTACK
FOLDED HEAVY ATTACK*
(*Assuming Thrust III. Thrust IV might drop Scab Mauler and Ogryn Reaper down to 2 stacks with bleed damage)