Icon of Sin (Doom Eternal)

The Icon of Sin returns as a boss in Doom Eternal, based on the boss of the same name in Doom II, and is the game’s final antagonist. The Icon was originally created using the heart of the Betrayer's son, as Hell's twisted way of honoring its bargain with the Betrayer to return his son to life. The Icon of Sin previously slumbered in Hell's Necropolis in Doom (2016), where it could be found as a dormant demonic edifice.

Tactical analysis
The battle takes place atop a ruined skyscraper on Earth. Unlike its form in Doom II, the Icon of Sin in Doom Eternal has a full body and can attack the player directly by slamming its fists down on the arena, shooting fireballs from its forehead, or sending out waves of fire; it can also summon other monsters to assist it. In the first phase, the player must attack eight different areas on its body - the right pectoral, left pectoral, right shoulder, left shoulder, right hand, left hand, belly, and head - in order to break off its armor. Shooting parts of its body which are already unarmored has no effect, so accurate weapons such as the heavy cannon and ballista are preferable for breaking its armor. The Icon's movements become faster and more aggressive as its parts are broken, so the smaller parts that move around more frequently (such as the hands) should be targeted early before they become more difficult targets.

In the second phase, the battle moves to a different building and the Icon can walk to different sides of the arena to attack. In this phase the player must attack each part of its body again, this time destroying its flesh and exposing the bone and gore underneath; as before, attacking a previously broken part of its body will not do anything and the Icon will speed up with each broken part. Additionally, the Icon will begin summoning more powerful enemies. In both phases, mobility is key for both evading the Icon's attacks and for finding an ideal position to attack vulnerable parts.

If the player's health or ammo are low, they should focus on the weaker monsters the Icon summons, using glory kills and the chainsaw to resupply as needed. Extra charges for the Crucible and BFG-9000 ammo are present as well, though these should be saved for use against stronger summons.

After the last part of its body is destroyed, the Icon collapses on the arena and the player stabs its exposed brain with the Crucible, killing the Icon of Sin and its evil once and for all.

Lore


Ancient Sentinel prophecies predicted the eventual return of the Titans, who persisted in slumber in Hell, seemingly immortal. As one of the Titans, the Icon of Sin is a force of chaos and destruction, and is considered a sign of the end times. The Icon of Sin in particular is described as being "forged from the essence of human suffering".

The Night Sentinel Commander known as the the Betrayer, in an attempt to free his son from torment in Hell, made an agreement with the Hell priest Deag Grav to lead the forces of Hell to the Elemental Wraiths in exchange for his return. Instead of giving back the son as expected, he returned in the form of the Icon, and Argent D'Nur was crushed and absorbed into Hell. The son's soul is said to be bound to his still-beating heart, which ties it to the Titan.

The Icon of Sin was resurrected by the Khan Maykr following the Doom Slayer's execution of Deag Grav, the final Hell priest, in a bid to continue the consumption of Earth. She constructed its Maykr-designed suit of armor in a bid to make it indestructible and to allow her to control the beast. However, when the Slayer destroys the heart of the Betrayer's son and frees his soul, all control over the Icon of Sin is lost, and it is said that if it is allowed to continue existing, it will eventually consume the entire universe, creating a super-massive black hole which will draw all of existence into Hell to be corrupted.

Trivia

 * The Icon of Sin's figurine is unlocked automatically after collecting every other figure in the game.
 * The Icon of Sin has clawed feet that are not normally seen during gameplay but can be seen in the model viewer, accessed by activating his figurine.