How to actually defeat the Cyberdemon in Doom 2016.

The first stage is fairly easy, you just need to avoid the rockets and airstrikes.
Save the BFG ammo for the second stage since is much harder than the first one.
Once the health is depleted, don`t forget to go to boss and perform a glory kill, otherwise the health will replenish back again.

Stage 2 is made up of 3 mini-stages:

First mini-stage
Is one where the boss will raise some stone walls and either shoot rockets at you or energy waves.
It`s worth to notice that you can escape the rock walls by strafing to the left or right, seconds after he raise them. Also the walls feature some sort of openings from which you can double jump outside of them.
To avoid rockets, again just run or strafe continuously either left or right. Do this so you won't get hit by rockets or energy waves.

Second mini-stage
You will notice it triggering when the boss will drop a bit of ammo.
Besides the above attacks, boss will try to fire it`s one-hit laser at you.
So be wary of it.

Third mini-stage
Is the most dangerous one since it will fire both energy waves and air-strikes.
I recommend using BFG in this stage because it will stagger the boss for a few seconds, giving you health some ammo and the chance to finish the boss off.

After you take down all the health, you need again to perform a final Glory Kill on the boss, which ends the boss fight, getting you the achivement:

- The only thing that drops from boss besides some ammo at the second mini-stage is 1 BFG ammo.

- For the first 2 mini-stages you can use shotgun explosives shots, mini-gun missiles or even the chaingun or gauss cannon. But shotgun explosive shots and grenades, do a decent job at taking the health down.

- If you saved some (BFG ammo) second stage (3rd mini one) will be much more easy for you.

- For the 3rd mini-stage after you stagger it with the BFG, shoot it with the rocket-launcer from a distance or you could try to super-shotgun from up close.

- Siphon Grenades are perfect for replenish some if not all of your health.

- Besides the health that drops from staggering the boss with BFG, there`s no other way to regain health (unless you're using Siphon Grenafes) so be super careful about it and try to preserve it.

- Lance.e.larson2:
"I believe there existed a glitch at one point that allowed you to fire off the BFG once and then hold the weapon wheel open to one shot him. See, the weapon wheels time slowdown effected the BFG projectile, but not the dps of the tracers, allowing for massive damage. I don't know if it's been resolved or not though."

- TheDoctah:
"There's no other way to regain health"
"Guess we're forgetting about the grenade built exactly for health regain.. Which I used a lot when I got hurt in the fight. Siphon Grenades may not nuke enemies, but they are darn good for keeping yourself alive."

- Yamapickle:
"Better idea. Use siphon grenades plus the "rich get richer" and "equipment power" runes. Make sure to have the upgraded equipment rune (can just spam grenades in a corner 30 times to get it, dont actually need to do anything with the equipment) as it gives you armor through the siphon grenade. use siphons to replenish armor, and keep armor above 100 for unlimited ammo. then just spam siege cannon blasts at it."

- Lennin a hand Cowhandcannon:
" I just used the (Gauss Canon) siege mode and lock burst the crap out of it and used the bfg stun to get out of the wall since it instantly cancels it."

- Rendroken:
"Stagger with bfg then shoot a bfg shot near it to do like half it's health."

- sqtuirtle:
"Ok guys, just do what I do spray him with the chaingun and shoot rockets."