I spent about 3 hours until i did that first time, my tip: go for the head, it becomes vulnerable when it does its energy attack

My cents:
-bring at least 3 mechs with railgun+accelerator ammo;
-do NOT engage the boss in infected zones. It gets a buff like regular enemies.
-Have one or two mechs with energy shield, it blocks the heat waves;
-When the boss charges at you aim for the head, if you do enough damage it should change course;
-Bring two mechs for crowd control and kill swarms of operaius. Be careful for when the worm circles you and spawns operaius. If it manages to surround you, try breaking out when its tails breaks the circle.

I can only confirm what was already said.
The most important part is to not fight the worm in the infected zone, lure him out of it first. Otherwise he will have MUCH more health.
Use as much railguns as you have / can carry.
Aim for the head! It is the only part that takes notable damage.
Bring lasers with fire mod against spawning Operarius.

How much armor the head have. I spelled onr hour shooting laser with no luck. Wish there is some damage number flying out to let me know what damage I am doing.

My rule of thumb is if you don't kill it within 5-10 minutes, you're not killing it at all. A boss won't take too long to kill if you are equipped properly, and will be impossible if you don't have the right weapons. Railgun is the most important weapon for boss busting, I find.

Originally posted by Hobo Elf:

My rule of thumb is if you don't kill it within 5-10 minutes, you're not killing it at all. A boss won't take too long to kill if you are equipped properly, and will be impossible if you don't have the right weapons. Railgun is the most important weapon for boss busting, I find.

Yeah, Railgun is what should be brought against all bosses in my opinion from my limited experience
If you use acceleration mod it has enough penetration and damage to punch through any target in the game, just put remaining points into firerate (Or maybe weight reduction since it can weight quite a bit if you plan on putting more than one at a mech)

In one run, I ran a single Castle fitted with two Shard Teslas, two Fire High Power Lasers, and the rest full of Shard Rocket Pods. It had the potential to kill a centipede in only two charges if I let it. The only reason I didn't do that is because I wanted to make sure I would get all the drops when it died.

But that's very late game.

In most cases, you'll want at least a single Plate running a Shard Tesla, a Fire High Power Laser, and an Acceleration Railgun. If you have a pilot specced into overheat mitigation and the research into processor programs completed, you'll also want to run the Kinetic RoF mod. Doing like this will guaranteed overheat the mech, but the tradeoff in sheer rate of fire for that Railgun is more than worth it. The Castle run also established that armor shredding combined with fire pools is valuable in itself, so if you have the capability to shred 200+ armor in a matter of seconds with any given loadout, you should absolutely run it. You will need this capability, as the centipede regenerates armor.

If your golden worm continues to rampage for more than 3 hours, please see a urologist