While you are making your way through Borderlands 3's first DLC, Moxxi's Heist of the Handsome Jackpot, you may encounter a slew of new weapons. Of these, a dozen are going to be Legendary guns that you can obtain by killing various named enemies. Some of these new legendary guns are going to be rather niche, usable mostly by those who build around the gun's unique effects. Other guns are reasonably good for most characters, though they aren't particularly flashy. Then there's the cream of the crop, the guns that can melt bosses even in Mayhem 4 without having to rebuild your entire character.
Borderlands 3 Best Guns Moxxi's Heist - ION CANNON
Effect: Charged shot deals massive damage
Dropped by: The Fabricator (boss at the end of Jack's Secret)
Most of the rocket launchers in the Borderlands 3 base game have proven to be underwhelming. They don't really do enough damage in the late stages of the game to justify their low ammo reserves, or have awkward effects. The ION CANNON rectifies this fact by offering outrageous amounts of damage at the cost of a nominal charging period. The ION CANNON is functionally similar to weapons like the Spartan Laser from the Halo series in this regard.
However, the ION CANNON can also score headshots and roll a double projectile modifier. You may also find that most variants of this Vladof Legendary have very good accuracy, letting it function as a Sniper Rifle as needed. This makes it recommended for Mayhem 4 as headshots virtually guarantee an instant kill on most trash mobs. One can only assume that Gearbox will nerf this gun in the future as it is that powerful.
Borderlands 3 Best Guns Moxxi's Heist - ION LASER
Effect: Shoots a continuous laser beam. Emits volley of projectiles when the gun stops firing.
Dropped by: Evil Saint Lawrence (Mayor's kill target in the Spendopticon)
Longtime fans of the Borderlands series know that a gun's displayed stats can often be misleading, especially when it comes to Legendary and other named weapons. The ION LASER is one such weapon. At first glance, this Maliwan SMG has exceptionally poor stats. However, what the weapon card doesn't say is that the ION LASER is a literal laser (although you could probably guess this by the name). You hold down the trigger and you've got a weapon that deals continuous damage at a very high rate until you stop firing. It's excellent for triggering any abilities that rely on you getting headshots, or if you want to melt generic enemies. However, expect it to be slightly less effective against bosses.
There are two things that you should keep in mind when using the ION LASER however. The first is that, in spite of the fact that the gun is a laser, it has recoil. You can manage this recoil with minimal effort, but it is odd nonetheless. The second, more pertinent note is that the weapon card does not account for the Binary prefix. Normally, the Binary effect makes it so that a gun shoot two projectile at once. Since the ION LASER is a laser, it doesn't actually fire two projectiles and thus isn't displayed on the weapon card. Instead, when damage from the laser is applied, the damage and ammo consumption is doubled (or at least that's the case when tested on the target dummy on Sanctuary).
Borderlands 3 Best Guns Moxxi's Heist - Craps
Effect: Randomly shoots a volley of projectiles
Dropped by: Jackbot (boss in the VIP Tower)
Generally speaking, guns with random effects aren't usually the best choice for Borderlands 3's endgame activities. An exception can be made for the Craps Legendary Torgue pistol, however, as its random effect can output a lot of damage. As far as can be told, the Craps functions like a normal Torgue pistol most of the time. It does decent damage with a fair rate of fire at the cost of a somewhat slow projectile speed. There's also a sticky projectile option that does more damage but delays the explosion of the projectiles.
When Crap's unique effect triggers, though, it basically turns one random projectile, sticky or otherwise, into a shotgun blast of explosives. The accuracy and spread of the unique projectile is relatively poor, but it's largely irrelevant given the normal effective range of the weapon. The likelihood of a unique projectile being shot is somewhat high too, hovering around a 30% chance based on rudimentary testing.
Borderlands 3 Best Guns Moxxi's Heist - Honorable Mentions
Effect: Extreme damage and ammo consumption per shot
Obtained by: Destroying all bottles of Torgue hot sauce
Effect: Explosive bullets
Dropped by: Claptrap Prime (Trashlantis boss)
Sometimes, a gun doesn't need to shoot lasers or melt faces to be viable in Borderlands 3. It could simply just do a lot of damage as its special effect, and that's usually good enough. The Scoville pistol and Boomer SMG fall into such a category by offering massive explosive projectiles. The downside is that both guns tend to run out of ammo in no time at all. In the case of the Scoville, each shot uses four bullets. For the Boomer, it's a fast-firing SMG that uses two bullets per shot.
The result is that you'll probably be reloading as often as you'll be shooting with these guns. Needless to say, this cuts into your DPS by a lot. Of course, if you have class mods or abilities that enhance magazine size or can regenerate ammo in some way, then these guns are fantastic. If you don't have access to such buffs, then all these guns will do is take up space in your backpack.