OP Harpoon Gun
The Harpoon Gun is the newest gun in the game and it's very very strong. Fan and Plentiful Combo make it incredibly OP.
Weapon and Ability
The Harpoon gun is ridiculously strong. I added the anchor just as something that could quickly charge up the Barrier, but anything else that could, like the Ancient Core, would also work.
Weapon
Primary Mod
Secondary Mod
Ability
Forge Mods
I went with Splitting Harpoons and Charmed Harpoons, but Plentiful Combo is really the only one you need to make this work. That + fan is basically infinite ammo with left/right click.
Charms
Fan is the main charm here. The second slot is just about making the kit even stronger. Fan + harpoons is insanely powerful.
First Charm
Fan is pretty non negotiable. You shoot a bunch of harpoons that charge up your combo points essentially immediately. You could potentially run Gold Converter early to add more blessings.
Second Charm
I run Thief's Eye until I get my build to the necessary OPness (11th or 12th level) and then try to switch over to Mr. Boom when I can. Doubles Meteor and thunderstrikes, as well as the anchor's smash.
Aspects and Blessings
Primary Aspect
Primary Blessings
Really you're trying to get as many of the flames as you can.
Secondary Aspect
You could switch lightning and fire but the idea is basically the same.
Secondary Blessings
Again, try to get as many lightnings as you can.
Ability Aspect
Barrier keeps you fresh as you'll be doing most of your damage with your weapon and also increases your stats.
Ability Blessings
Again, we're just trying to add what we can barrier wise. Energizing Barrier is the most useful as it will help you shoot faster. The point of this build is that you should just be alternating left click/right click as fast as possible until everything is dead.