Loader's Scrap Barrier ability combined with attack speed can provide a ton of constant temporary hp, as well as mowing down enemies as easily as a one-shot build.
Build of Attack Speed Loader
Why Attack Speed Instead of One-Shotting
Loader has a unique ability where every time you attack something by using Knuckleboom, Spiked Fist (not actually sure if spiked fist works, needs to be verified), Charged Gauntlet or Thunder Gauntlet, you gain temporary hit points. However, the amount of temporary hit points gained is not determined by how hard you hit, it gives you the same amount of temporary hit points whether or not you deal 40k damage or 2. This makes it easy to have massive amounts of health without any infusions, so long as you can attack fast.
What You'll Need to Get Past the Early Sections
Artifact of command is a must for this build, or you will have to depend on insane luck to get the items you need.
It is also recommended that you have Gesture of the Drowned unlocked, though it may not be required.
For your starting items, you are going to want to grab 6-7 Lens Makers Glasses for your white items, at least 2 fuel cells for your green items, and a 57 leaf clover for your first legendary.
To get an early legendary, you are going to want to find the newt altar on either stage 1 or 2 so you can do the Void Fields. If you have Gesture of the Drowned unlocked, you are going to want to buy 3 of them from the Bazaar Between Time, as well as a Spinel Tonic (if they have a usable lunar item available in the shop). The 3 Gestures, combined with 2 fuel cells, will make it so Spinel Tonic lasts forever, and this can be a huge help if you are trying to unlock Loader's skin in monsoon.
After the First Items
Since your Spinel Tonic activates constantly, 2 war horns (possibly 3) will be able to allow you to have a permanent 70% bonus to your attack speed, on top of the Spinel Tonic's bonus. Once you have enough Lens Maker's Glasses, you are going to want the same amount of Tougher Times in order to minimize the amount of damage you take. After the 2 war horns, you are going to want to stack 3 Predatory Instincts to go with the crit chance from the Lens Maker's Glasses. The Predatory Instincts are going to be adding much more attack speed, which combined with the Tougher Times, will allow you to be incredibly tanky. Once you have the Predatory Instincts, you should go for mainly infusions, but a few Harvester's Scythes would also work. Any other legendary you like will be fine with this build (Dio's Best Friend is still going to be recommended above all others in Monsoon), but do not grab Shaped Glass at all. It will halve the amount of temporary hitpoints you are able to get as well.
This build was able to get me to the Obelisk on Monsoon, as well as beat the Twisted Scavenger. It does slightly rely on luck, in hopes that you don't get something that is terrible to melee for a boss.