Icon of Sin/Doom Eternal

Background
Near the end of the game, Samuel Hayden informs the Doom Slayer that Khan Maykr is awakening the Icon of Sin as a last-ditch effort to destroy the Earth. To stop this, the Slayer travels to Urdak and confronts the Maykrs as they complete the ritual to awaken the Icon, intending to control it via the mortal heart of the Argenta it used to be. Using a knife given to him by Valen, the Slayer destroys the heart, causing the Icon of Sin to go berserk and travel to Earth independent of the Khan's control. This also breaks the Maykr's pact with Hell, allowing demons to invade Urdak. After slaying Khan Maykr and returning to Earth, the Slayer battles the Icon of Sin atop a skyscraper, destroying the Maykr-made armor protecting it. Once the armor is fully destroyed, the Icon of Sin teleports to a different location; the Slayer pursues it to continue their battle. After a lengthy battle that results in most of the Icon of Sin's flesh being destroyed, it is left weakened enough for the Slayer to climb onto its head and bury the Crucible into its exposed brain, breaking off the blade to kill the Titan for good.

Codex
The Icon's presence warps reality, damaging the intricate order of our dimension merely by existing within it. If the Icon is allowed to remain unchecked it would lead to the total devastation of Earth, followed by a breakdown of spacetime around the planet. The resulting black hole will eventually drag our entire universe down, casting it into the mouth of Hell as a conquest to be absorbed by the Dark Realm.

The Khan Maykr had taken measures to augment the titan, installing Maykr technology throughout its structure to ensure it could be controlled. With the ritual interrupted the Icon is now fully unleashed, raging across Earth until Hell consumes all. No longer bound by the Heart of the Betrayer's Son, the Icon of Sin is free from any measure of control that the Maykrs might have conceived. Only the Slayer, prophecied in Argenta legend to stand against the Icon, can stop this apocalypse.