Sonya Mazda/Labyrinth of Chaos

Sonya Mazda is the apoptosis/angelic counterpart of Sonya's alternate forms.

Biography
She is a boss encountered in the Labyrinth of Chaos. You cannot talk to her, there is no rape scene if you're beaten by her, and you can't beat her (well, you can beat her, through exploiting a skill called Vicarious Clara. It provides a shield which blocks all damage to the user for the next three attacks, and can also be stacked).

Strategy
As said above, you shouldn't be able to beat her. But you can, through lots of grinding, and exploiting a skill called Vicarious Clara (you can unlock that through the Necromancer Job. She is one of the easier bosses in the Labyrinth but is by no means weak.  You want all of your characters you bring to the fight to have access to Vicarious Clara. All of them.

Fight her like you would any of the LoC bosses. Including the rest of the super bosses, like Reaper. However, you want to take some other things into account:
 * She has a multi-hit holy attack which also inflicts ascension. What ascension does, is kill you. No matter your health, you're simply removed from the battle. Good news is it isn't guaranteed to hit, and you should have Vicarious Clara up to protect you if it does. The bad news is it lands four times. So if you have the misfortune of her using it before you get Vicarious Clara up, expect casualties.
 * She has a self-buff which can do a variety of things. The worst is arguably the buff that increases her pleasure, which just so happens to be one of the two attributes she is weak to (I know physical and holy damage her, but the resistance is so high, you should never be using them). She has an agility buff, which means she is more likely to attack before you can, but it's not all that bad assuming you already have plenty of Vicarious Clara's up. If you don't, well, that's too bad. Her magical evasion buff can be a pain, as it reduces the chance of attacks which are typically guaranteed to hit from hitting her, such as dark energy attacks. Finally, she has the accuracy buff. Do you remember that Ascension attack mentioned above? Well, what this attack does, is increase the chance of that hitting. Not good.
 * The next one is an attack which is guaranteed to hit and inflicts ascension. And it hits the entire party. How do you counter this? Well, you can't. You just hope it doesn't inflict ascension. Potentially, you could bring a Fox Geisha with you, like Nanabi. She has a skill called Anti-Death Song, which gives you immunity to this attack and all other expel attacks for ten turns. In fact, you want to bring a Fox Geisha with you. So it can be countered after all.
 * Next is her freeze attack. Freeze, as you would expect, prevents you from taking action for three turns. You want to counter this by bringing someone with access to a skill which resists it. Such as a SeaDragon Dancer, like Sully. A Seadragon Dancer is preferable, as they also have access to Timewarp dance. The skill which resists freeze is called Resist Freeze, in case you were wondering.
 * She has a skill which inflicts a single target shock, but this shouldn't be of concern. Vicarious Clara should deal with it. But if you're concerned about it, the Battle Master has a skill called Resist Shock. But you should bring a Battlemaster despite this.

The video will provide a tutorial on what you should do exactly, and who you should bring to the fight. The guide will give you basic information.

I got most of the information from the guide and the video. Both are extremely helpful, and I'd highly recommend you check both of the guides if you're serious about beating any of the LoC bosses.

Trivia

 * Nothing is confirmed about her in part 1. Nothing. Only that she is possibly Sonya, but she could be Karen for the all the information we know. I say, Karen, because Adramelech is likely Karen, and both Adramelech, Sonya Mainyu, and Sonya Mazda possess a horrific scar on the side of their face. But whether this is a trait shared by all of Sonya's families alternate forms can't be said either.