Cyberdemon/Doom 3

"Witness what will be unleashed on Earth!"

- Betruger

The Cyberdemon is the final boss and most powerful demon of Doom 3. It is found at the Primary Excavation Site, where it stands guard over the massive Hell Hole.

The Cyberdemon did not make an appearance in the expansion pack Resurrection of Evil, so the one that was killed at the end of Doom 3 was presumably the only one.

The Cyberdemon is also the only monster from the original games to be a boss.

Physical Appearance
It stands roughly 20 feet tall, more than 3 times as tall as a human soldier. While the Cyberdemon overall retains its appearance as a minotaur-like giant, there are some differences of this new incarnation of the monster compared to its classic counterpart. This incarnation has a long tail, extending from the machinery on its back, and both legs are mechanical - as opposed to its original version, whose only mechanical leg was the right one. Another noticeable difference is that its rocket launcher is now located on the right arm instead of the left one.

Combat Characteristics
Like its original counterpart, the Cyberdemon attacks by firing a salvo of 3 consecutive rockets from its arm-mounted rocket launcher. Unlike the original version, it now has a melee attack as well: the monster can stomp on the player, doing a whopping 400 damage and killing them instantly.

Unlike its original counterpart, this Cyberdemon is completely impervious to any of the player's weapons (even a fully-charged BFG shot has no effect on it). Instead, the player has to utilize the most powerful weapon in Doom 3, the Soul Cube, to kill it. The Soul Cube states that only it can kill "Hell's mightiest warrior" referring to the Cyberdemon. It takes 4 hits from the Soul Cube to kill the Cyberdemon.

Strategy
The basic strategy for taking down the Cyberdemon is to always be on the move. Do not stay for too long in one place for any reason or the Cyberdemon will nail the player with its rockets. The player's stamina does not decrease near the Hell Hole, so take advantage of this and use sprint constantly. The Cyberdemon's rockets are fast, powerful, and long ranged, but fortunately the rocky spires around the Hell Hole prevent the Cyberdemon from getting a clear shot at the player. However, do not get too close to the ledges as the blasts from the rockets can knock the player into the Hell Hole to their death. Also, do not even think about going near the Cyberdemon: its stomp will crush the player instantly.

Throughout the battle, the player will be constantly attacked by Imps and Maggots, which will either teleport in or come crawling out of the Hell Hole. The player should kill these demons as fast as possible to get the player's Soul Cube operational. Use the rocket launcher or the BFG to one-shot these demonic lackeys. No need to worry too much about picking up any health units on the ground, since the Soul Cube will heal the player. And remember, always stay on the ground and keep out of the Cyberdemon's line of sight until the Cube is ready.

Once the Cube is powered up, turn around and face the Cyberdemon itself. As soon as the Cube has been launched, get out of the Cyberdemon's line of sight and start running again. Be sure the player's targeting reticle is focused on the Cyberdemon before launching the Cube. If there's an Imp or a Maggot nearby, the Cube may end up going for it instead of the Cyberdemon, thus wasting the player's shot. The Soul Cube can also briefly stun the Cyberdemon upon contact, which you can use to your advantage to put distance between it and yourself. A good idea would be to leave the Soul Cube charged before starting the level and having it equipped before the boss intro. Upon the end of the cutscene, immediately use the Soul Cube and sprint to the other side of the map.

After four hits, the Soul Cube will chop off one of the Cyberdemon's legs. It will then cut into its head, killing it. Afterwards, it will fly into the Hell Hole which will them erupt with lava and the entrance will solidify. Thus, you win the game.

Trivia

 * The Cyberdemon can be found in the game files of the Doom 3 expansion Resurrection of Evil, but when it's spawned (for example by using a cheat code), the Cyberdemon appears to be vulnerable to regular weapon fire, requiring lots of rockets, BFG blasts, or Plasma gun cells to the head in order to fall.
 * Logically, the Super Shotgun may work against the Cyberdemon, but it isn't recommended due to the instant-death stomp attack the Cyberdemon possesses.
 * The Cyberdemon is referred to as "Hell's Mightiest Warrior" by the Soul Cube, although the Maledict has nearly twice as much total health and more attacks. This is likely because the Maledict is vulnerable to normal weapons.
 * If noclip is used to get close and you punch the Cyberdemon, blood will come out of the robotic parts.
 * The Tyrant's front and back glory kills in Doom Eternal could be a slight nod to the Doom 3 Cyberdemon's death, as both involve having a leg severed and being struck in the head by a supernatural bladed weapon.
 * The Cyberdemon's stomp is the most powerful attack of any enemy in the game.