She is, at this point, in the sky over Avernus, that plane where every soul that comes to Hell appears. A significant distance up in the sky, to account for melee attacks.
Every new-come soul to Avernus is Healed, and restored to another life wherever their death may have been.
Every one of the infernal citadels that dot Avernus crumbles into dust.
The Promised Land, haven of Barbatos and trap beyond all traps, disintegrates as the lashing white worms that make up its soil are restored to full and true existence on whatever plane they once hailed from.
Where gates to Dis stand at the wrong angle, the light of Life passes through, and the city of markets crumbles as the slaves that are their literal foundation arise wherever, and on whatever world, they passed from it.
... And, if that was all, then Hell would not have been so injured; but Hell's fate is still worse, for just as she unleashed that curse the Second of the Nine (hoping to strike her down before this could be accomplished) had drawn her back with another Wish, a Wish that placed new rubies in the hands of his eight compatriots, to bind her again beyond the power of any mortal and trap her in Hell's foundations forever, there to meet the fate of those who oppose their Lord.
For devils are forged of souls, and each of the pit fiends that stand by her was once a great mass of lemures new-come to Hell, a blobs of flesh that was once a great villain, forged and mangled together until one entity had all the cunning and power and cruelty of every soul that went into forging it. It would take a great deal indeed to unmake a devil, for their true identity is now infernal; whatever mortals they might once have been are gone, and this new devil cannot be unwoven by... nearly... any means known to Pharasma's Creation.
It would, for instance, take a full blast straight in the face of the mightiest Life-light that Lucy might use to restore herself while under attack from a whole lot of apostate devils who weren't quite enough to shatter her mind completely, but where that was an active risk if she kept going.
About, say, a quarter of the strength of a main sequence star?