Omen

Omen, a corrupted being evolved out of the remains of improved Lazarus dumped in Nexus after getting exposed to Grace’s blood. He gained his persona from drinking Grace's blood. His body was ever changing and could take any form so long as his brain (which was separated from his body) was soul-linked to his body. He searched for Grace and claimed to be blessed by Ridenti Virgo who shaped him herself. He believed it was his mission to awaken Grace and free Aezathol and save poor souls of the world from the shadow(c81). He is chivalrous but has no patience with anyone who doesn't believe in what he does, calling them heretics. He still showed a brief period of loyalty to his Majesty, Bonnie, a result of the blood from the 3 princesses Lazarus was born of(c78). He appears in the shape of a young to middle aged man, wearing sun shades and a priests dress giving him the appearance of one of the Organization's men. He also has the tendency to speak in old English. His name granted to him by Ridenti Virgo is unspeakable, just a loud screech so he first called himself hunter, but liked the name Omen after Clover mistook him for one of the Organizations men. (They call them Omen in Alphonse)He possesses the ability to suck/devour an opponents Yoki and make their powers/abilities his own, an ability he gained from Grace as Aezathol wanted to use him to increase Grace's, and by extension, her own power since Grace refused to use the "Heart of Darkness". He began kill in Nexus, devouring countless of Yoma, corrupt moss, rodin, and many other corrupt beings, gaining the ability to elongate his fingers and use rodin's mace and complaining these would only increase his Yoki quantity not quality so he searched for advanced corrupt beings(c78). Eon gave him the ability to switch between heightened defense to strong offensive abilities. His strength was fearsome enough to make the injured Cassandra and Faith  ran away instead of facing him. He killed Lancelot, Charles, Laila, and an Outsider in Nexus, gaining their abilities, making him stronger. He entered Noble's castle through the elevator between the castle and Nexus and continued to kill awakened beings. Self-destructing Clovers proved fruitless in halting his advance and he was crushed in by a wall of Shield beings, only to escape by using a second detachment of himself, Wormwood which allowed him to escape and kill everyone in the room. He attacked and killed Poe and almost killed Bonnie before he was reduced to splinters by Noble. He waited until Grace arrived before revealing that he hadn't actually died, but had been using a decoy. He tried to synchronize with Grace to force her to release Aezathol but he was pushed back by Faith, Gloria, Cassandra, and Clarice. When Clarice tried to kill Grace, he ran to stop her, ignoring any damages to his body. He gained dark sclera and tattoos, claiming to be an angel and later a god, demonstrating a newfound ability to reverse all damage on his body by screaming "I reject". His detachment, Wormwood, which was the guardian which kept the souls he had absorbed in check, was defeated by Diva and he lost control over his form and abilities taken from the people he killed. Aezathol excitedly told Grace to kill him, her intention being to become stronger by absorbing Omen's seasoning which he had taken from the beings he had killed. Omen, weakened, transformed and reverted to his Outsider form taken from the outsider he killed in Nexus. He towered above Noble's castle and proceeded to attack it. Quickly, Noble, Alice, Miata, Arwen, Artemis, and many other awakened fought and defended the castle (note Deborah doesn't "fight" although she played a critical role in defeating Omen, restricting his movement). Omen dropped many corrupt corpses, corrupt worms and another detachment named prophet, the voice of omen, from his body which attacked the castle defenders. Meanwhile, Grace was trapped in Omen's central heart, fighting him in a mental battle. After killing him by reclaiming what he had taken from her when he drank her blood, his body collapsed and his mind was destroyed. However, Lazarus survived, furious that Omen and the ability to die had been robbed of him, and attacked Grace, almost killing the exhausted claymore. However, his body was destroyed by Faith and his brain by Bonnie, resulting him bursting into flames and dying, his last words being "Live, Dark one". His body was disposed of by Alice into Mt. Isley and his corrupt minions were cleaned up and burned. Omen claimed that he had barely used even a fraction of Aezathol's true power and couldn't understand why Grace wouldn't voluntarily awaken. Miata claims that Omen singlehandedly killed more awakened beings than any number 1 in the history of the organization.