(the following is based on untranslated portions)
On the Alice route, Sonya Mazda absorbs dark energy from Morrigan to become Sonya Chaos. Sonya Chaos summons Adramelech into the world, whom the Lilith Sisters and three Seraphs team up against. Luka's party fights and defeats her, but Adramelech persists (thanks to her ability to self-resurrect) and the world is gradually swallowed up by Chaos. Nuruko then reveals her true form as the Spirit of Chaos and reverts Sonya Chaos back to the (outwardly) human Sonya.
On the Ilias route, Sonya Mainyu absorbs holy energy from Gnosis to become Sonya Chaos. As in the Alice route, she summons Adramelech and is defeated by Luka's party. However, after being defeated, Sonya Chaos regains her personality as Sonya. She attacks and manages to defeat Adramelech, but receives a mortal wound in return. Sonya Chaos reverses the damage to the world and creates a copy of a Sonya from another world so that Luka won't miss her. She then dies.
If Luka loses another Ilias appears with a much more different form than usual, assuming this is another version of Ilias from another time after Morrigan kills the real Ilias from the true history.
"Sonya after awakening as an XX-type Apoptosis, her absorption of holy and dark energy has changed her into this form. This fusion of holy and dark energy exerts such a tremendous force that, if left unchecked, threatens to destroy the world. There are many uncertainties surrounding her existence, most of which are shrouded in mystery."
- Attack – One Foe
- Garden of Earthly Delights – All Foes, Auto Hit, Holy, Pleasure Attribute, Seduction 50%
- Heavenly Demon Revival – One Foe, Auto Hit, Holy Attribute, Ascension 30%
- Solar Eclipse – All Foes, Magical, Bio Attribute, Mini 50%, Petrify 50%
- Holy Flare – One Foe, Auto Hit, Holy Attribute, Ascension 10%
- Shadow Flare – One Foe, Auto Hit, Dark Attribute, Death 10%
- Apoptosis – One Foe, Auto Hit, Holy, Dark Attribute
- Zero Shift – All Foes, Auto-Hit, Dispel
This is it, the final boss of part 2. Unlike the previous final boss, Sonya Chaos can put up more of a fight. Firstly, most of her attacks are auto hit, so relying on dodging them is out of the question. Next, all but 2 of her attacks inflict dangerous status effects. Death and Ascension speak for themselves, but Mini completely shuts down physical attackers and Petrify flat out removes the character from battle unless you use a turn to cure it. Thankfully, the attack it is on is a magical attack, which can be reflected. Like most of the bosses up to this point, Sonya Chaos has a dispel, but hers is better, it also resets any stat debuffs or elemental weaknesses she has, forcing you to reapply them alongside restacking buffs. As for actually dealing damage to her, Sonya Chaos takes 25% less damage from ALL elements except Bio (which she nulls) and Sonic (which is her only weakness), so if you got a strong Sonic dealer person, that's the way to go.
"Nice to meet you, Luka. I am a goddess, the beginning and the end. Sonya Chaos uses powerful offensive skills. Holy and Dark elements are difficult to deal with, you'll have to survive them. She has normal resistance against physical and Pleasure attacks but others are a bit ineffective. Refrain from using ineffective attacks as much as possible. Status ailments work next to never on her. However ailments that reduce her stats work so use those. Well then, until we meet again, Luka child of destiny. May you wield your sword in the service of the Light."