If you’re coming to this guide, hooray! The worst of it is over.
Even if you’re on your first encounter with the guy on arc complex or you find yourself struggling to kill him for the umpteenth time in ancient gods, you’re 3 hot swaps away from mastering DOOM.

The marauder is a super heavy demon with one of the most complicated move sets in DOOM, so let's break them down real quick.

The marauder has four attacks: A crucible-style axe, a SSG, and a flaming hound, and a glowing red projectile thrown from the axe. These are all triggered under different circumstances, but nonetheless hit like a million bricks moving very, very quickly.

If you stay too close, the marauder will fire his shotgun, which will dish out a hearty dosage of damage, as well as faltering your movement.

If you’re too far away for his other attacks, the marauder will periodically fire a giant red arc, which deals relatively significant damage (but is easy to dodge!)

That ♥♥♥♥♥♥♥ Dog spawns seemingly randomly, however, the circumstances to spawn it are actually pretty easy to decipher. You may have noticed that when you shoot the marauder when its eyes aren’t glowing, he will bring up a shield and block your attack (this includes hitscan, i.e. ballista, bfg tracer, chaingun, ssg, etc.) It’s this shield motion that causes the dog to spawn. You can avoid spawning the dog entirely by only attacking the marauder during the vulnerability period.

In short, whenever the eyes flash green, the marauder is vulnerable to your attacks. This occurs when swinging his axe to hit you, and shooting him will falter him and cause him to stop attacking, allowing you to easily rack up some damage.

It sounds paradoxical, don’t go far, but don’t get too close, right? In reality, it’s not difficult to get into this goldilocks zone where you can frequently trigger the axe attack. Think about the effective range of your SSG, and then stay just out of it, continually backing away and waiting for the opening.

Now for the fun part, exacting revenge for all the times the marauder cut you down to size with that annoying ass dog.

Your best friend is two words: Hot-Swapping.
I HIGHLY recommend the hot swapper perk if you don’t have it already, it will make the fight (and the rest of the game) so much easier.

Useful key bindings (For both ESDF and WASD users.)

Blue = Ballista
Red = Super Shotgun

Optimizing your keybinds to more efficiently hot swap will make killing the marauder much easier with this method (and also you should just do it anyway, seriously, go rebind your keys right now)

Once you have faltered the marauder with your ssg, hot swap to the ballista, fire, and swap back to the ssg again for one last hit. I recommend using a dash to get close (so that all pellets connect) and then using your other dash to get out of the way once he is no longer staggered. Rinse and repeat until glory-killable or dead. It’s that simple, really.

And yes, there are technically more efficient combos which can even one cycle the marauder, but this is the easiest to explain and the simplest to execute.

Hope this guide helped you!