How to Defeat Doom 3's Bosses

Tackling the Vagary (Spider Boss)

When you enter the battle, start throwing grenades until you are out.

Then, take out your chain gun and finish her off.

Another way to kill her is to use the plasma gun which CAN be found in that level. Be careful to avoid being hit by the things she throws at you.Defeat Doom 3's Bosses Step 3.jpg

Killing the Guardian

Know that the Guardian is NOT blind as many people think, And he uses the Seekers to find the Soul Cube. Kill the Seekers first so he has to project his vulnerable soul and create more.

Strafe quickly around the large walls, while aiming for the flying seekers. Shoot those first before they have a chance to see you.

Learn that when he is making more, he will project his soul above him to create the Seekers. Quickly pull out your rocket launcher and shoot the glowing avatar on his back. If it is red, it means he is being hurt. If you found the BFG earlier in the level, charge up a BFG shot (hold down fire) and release it.

Know that if he is able to make more seekers before you kill him, you should kill those immediately.

Sprint often. It seems in Hell, you can sprint for as long as you want. Sprint around to dodge the Guardian's attacks if the Seekers spot you.

Understand that this boss is a very strong boss and has many strategies in defeating you. You will have to use your knowledge and common sense to defeat this maniacal personagem.

Defeating Sabaoth (Sergeant Kelly)

Use the pillars as cover and unload rocket fire at him.

Avoid touching the pillars. Touching these will result in electrical shocks. You’ll also want to steer clear of the fire pits as well.

Run and strafe constantly to avoid being hit by his BFG.

Shoot constantly at the Sabaoth's upper body, and when he fires his BFG, keep shooting, but aim for the BFG shot instead. If you're are fast enough, the BFG shot will explode in the Sabaoth's face, causing major damage. Do this three or four times, and the Sabaoth should drop.

Defeating Cyberdemon

Remember that you got the soul cube earlier on in the game. It is filled up by killing other demons, who’s souls go into the cube.

Avoid using the soul cube when you first begin the fight. You have to use a different weapon to kill normal demons in order to fill up the soul cube. To do this, simply strafe around the edge of the hole and kill demons as the come up. Be careful not to let them overwhelm you.

It takes five kills to fill up the soul cube

Once the soul cube is full, "aim" it at the Cyberdemon (you want to hit him, not waste it on a useless target like some imp running around)

Hit the Cyberdemon 4 times with the Soul Cube to kill him.

Sit back and watch the end cutscene. You just beat the game!