When you fire the rocket launcher, you get a relatively slow moving projectile that deals about twice the damage of the shotgun with a direct hit. Splash damage does around 300 damage, direct hit 100ish. So getting a direct hit does a good chunk of damage. And this can be done from a pretty generous distance, making it a great opener. However, to ensure the projectile actually connects, you want to damage the enemy before it hits, making it "flinch" and stopping it from dodging. To do this, you simply fire the rocket, swap either the combat shotgun or the gauss cannon, and fire. If you pull the trick off right, you hit the enemy with two shots at once. Doing this one-two punch will flatten Revenants and Hell Knights even on Nightmare. Add in a final blast from the Super Shotgun to finish them off if that doesn't take them out. For slightly beefier enemies like the Cacodemon, you may want to hit them with a shotgun cluster grenade while you're at it. To be honest, you can even swap back to the rocket launcher and fire another one off if it's done reloading. Just be wary of swapping back to Gauss, because it has a ridiculously long cooldown in between shots.
Against heavier beasts like the Mancubus and Barons, the Remote Detonation and Lock on Burst really shine. Remote Detonation nearly doubles the damage when mastered because of the second explosion it generates. It's a pain in the ass to unlock, but 100% worth it provided you can avoid self-damaging too gratuitously. Lock-on, while not quite as good, is also extremely viable. you can fire off a single rocket and charge the burst while it travels, effectively unleashing a four-rocket salvo, then resume weapon juggling. The only weapons that don't really fit into this are the Heavy AR and the Plasma Rifle, but the Plasma Rifle's Stun Bomb can help get you the breathing room you need to start doing weapon combos against Barons, who are a hell of a lot faster (no pun intended) than they have any right to be. Additionally, Micro Missiles are ridiculously handy for clearing out smaller packs of baddies like Imps/Soldiers/Razers/Possessed.
Having customized keybinds will facilitate this greatly. If you've got a mouse with those little forward/backward buttons on the side, binding Rocket launcher to forward and Gauss to backward lets you access those much faster than having to reach halfway across your keyboard's number row. I personally also bind SSG to control, chaingun to shift, Combat shotty to 2, Plasma Rifle to 3, and heavy AR to 4. With all this being said, the moment you get the Rocket Launcher the weapon quick swap suit perk becomes a must-have. Faster weapon swap means much more dps.
All this may seem a bit convoluted, because it kind of is, but I guarantee you that weapon swapping playstyle is infinitely more satisfying than just running around spamming siege mode. That's why I'm kind of glad Doom Eternal is adding counters to that kind of cheesing strategy. I get that not everybody wants to go full Clockner, but having the game encourage/compel the player to more effectively utilize all the tools they have at their disposal should address Doom 2016's biggest flaw, i.e. the cheesability of late game, in a smart and effective way.
