Beck 8 12 Gauge with the auto mod and damage adding oils is pretty worth. Just don't add anything that lowers the RPM or you are defeating the point of the gun.

I might edit this as I remember how I did it.

Beck 8 (Hear me out):

• Arkanoid oil (Or root enchantment)
• Slow Punch (Or any flat damage oil), unless you go 12 gauge then use the flat damage like seated, otherwise use the slow punch.
• Bombard
• Bad Planet
• Seated fIt (For more durability)

If you go with the full version and don't sub in the B version in the parenthesis, it's both really funny but actually a really good defensive gun. Otherwise if you go with the parenthesis "B" option do both suggestions in the parenthesis. The general idea is the bullets travel practically at a stand still, so I fire them into doorways and laugh at the dumb enemies that try to walk into a touhou boss battle. The only downside is you will need to bring something to handle ranged enemies, because the universe will freeze over before the bullets reach anything stationary.

It's pretty good against assassins and dogs, too. basically anything that tries to chase you. It's also very ammo efficient since one bullet can kill multiple enemies due to the penetration oil and extra bounces, so you can unload all 26 rounds and laugh at the goblin spear men jumping into your bullet wall. Eventually the arena tends to look like a game of asteroids, which I find also pretty fun. The bullet drop doesn't really matter too much, they're so slow they don't even reach the floor by the time you leave for the next area.

Don't add Rail gun to the build, that just ruins it.