dropping my AU because I wanna actually do something with it lmao.
Before the megaspells fell, she utilised King Sombra’s spells to protect and seal the crystal empire. Since then as the wasteland has gotten more and more depraved, she’s more or less lost the use of her love magic and there is no love powering the heart, so her ‘dark’ magic and manual work of the crystal ponies is the only thing keeping the empire going. She has a deal with the Enclave in exchange for food and additional protection, they provide the Enclave with the crystals that power the magical energy weapons.
With the remnants of the shattered crystal heart, Cadance has her own magical energy weapon that, alongside her magic, she helps protect the empire with.
Shining Armor has been turned to crystal, and is hidden somewhere in the palace to protect him. Cadance doesn’t know if the spell has killed, or saved him - it isn’t time to try and reverse it yet.
The crystal ponies themselves are…doing ok. They work in the mines and create the magical energy weapons, and alongside Cadance and the Enclave soldiers posted in the Empire, fight to protect it.