(okay then, here we go)
(assuming that somehow, by whatever magical means you want, Roxana sees this)

Sabrina and Lythala teleport back to the palace of Asmodeus, and Sabrina goes into an audience with Asmodeus himself. She outlines the plan that Askaretha has to attack him, and as she details everything, Asmodeus planners arrange forces to stop her. As they finish, Asmodeus stands With what you have given me, I will crush that upstart, I knew I had promoted her too quickly, and after this is done, I will reduce her to lemure status with her memories intact, so that she can suffer her humiliation for centuries. And you two will be at my side to watch it happen.
The next day, as Askaretha's forces move on Asmodeus, she is shocked to see his legions prepared and waiting for her, as they both stand on craggy peaks overlooking the battle field. You will now pay the price for your treachery In desperation, Askaretha looses power from the Gem, it washes over Asmodeus and his general staff, doing some damage but nowhere near enough to knock any of them out. He laughs, and prepares to cast in retaliation....but it never happens.
The blast of force had stripped him of his protections, and before he can cast, a long sword protrudes from his chest where his heart would be and a second one slashes him across the neck, severing it completely. Without even knowing why she is doing so, Lythala grabs his staff as it falls from his hand, and touches Sabrina to teleport them both to Askaretha's side. Dumbfounded, the forces of Asmodeus hesitate for a moment, and Askaretha fires again. This time, she aims at the mass of his forces and staff, and this time, she unloads the entire stored power of the Gem, making the first shock look like a firecracker, compared to a nuclear blast. The whole Gem is emptied, it falls to the ground a broken lump afterwards and the blast devastates the Asmodeus host. What few ranking devils survive suddenly decide that somewhere, anywhere, else is the best place to be and they teleport away, leaving whatever is left leaderless and they are fallen on by the host of Askaretha and Glasya. In a grand sweep, Askaretha has destroyed Asmodeus and taken his symbol, his staff, making her the new Queen of Hell.
Sabrina turns and addresses Lythala and by extension Roxana. You once told me that a secret told to more than one person is no longer a secret. And thats why we could not tell you. Your reactions, everyone's reactions needed to be genuine. Otherwise, there would be no way that I could get close to Asmodeus. Lythala, you knew nothing, even the "sale" of you was a sham, all that we did was implant a subconscious order during one of our sex hypnosis games to grab the staff and teleport us out. When you were "sold", it stung and we counted on you advocating for myself to your new master. Roxana, you knew nothing as well and it was needed that no one in the court see what was happening. Even Glasya didnt know, she was allied with Askaretha and joined in some small way in the attack, but she was used as a conduit for false intel to Asmodeus. I hope you can forgive us.

In the weeks that follow, many more changes occur in Hell. In the first layer, Bel retains his position, this archdevil held himself above the politics of Hell and since Askaretha is moving to advance even more forces from the dukes to his campaigns, he is more than happy with the change. Layer two was controlled by Dispater, and as the first archdevil to make alliance with the up and coming Askaretha, he keeps his power, in fact, he is able to reduce his paranoia. Layer 3 was controlled by Mammon, but the archdevil suffers a fatal accident, and suddenly, Tiamat takes over his fortress, rebuilding it in the fashion of her old fortress on the first layer, and now instead of being resident of Hell, she is granted archduchess status. Layer 4 was co-ruled by Fierna and Belial, however Belial suddenly finds himself completely without authority, instead of being at least the nominal leader. Fierna was long an ally of Glasya and thus, by extension, Askaretha. Layer 5, Askaretha's old level, is handed back to Geryon, who ruled it before Levistus, his return to glory ensuring his eternal loyalty. Layer 6 was ruled by Glasya, as the #1 supporter of Askaretha, she continues to rule in this layer and is clearly Askaretha's #1, in many ways could be called the Princess of Hell. Layer 7 was the abode of Baalzebul, and while he still rules there (having had no love for Asmodeus) with Askaretha promising to research a way to reverse the curse Asmodeus placed on him, he also must check all major decisions with his first consort Lilith, who owes loyalty to Askaretha, because of this promotion. Layer 8 was ruled by Mephistopheles, but Askaretha knows he will never bend a knee to her and he, like Mammon, suffers a fatal accident at the hands of his consort (which is just an unproven rumor) Baalphegor, who takes his place. And, of course, Askaretha takes over the 9th plane