The Queen:
 
Once known as the Princess of friendship, Black Nova is the new queen of Equestria.  
Expert and talented in the use of magic, she has total control over the day and over the night, and is said to be in a position to even change the weather.  
After defeating Celestia, Nova decided to keep Canterlot as headquarters of her dark, cold and ruthless realm.  
The lands that comprise it ranging from the Yaks Realm to the arid lands over the Scorching Desert, and anyone under her control is forced to a life of misery … or rebellion.  
The resistance movements (such as Stee hoofsl or thundering clouds) are increasing, and Nova knows that this will cause major problems.  
But for the moment, everything remains under control, and so will remain.  
Although not for much longer …
 
A disease is afflicting her kingdom, to which even the tyrant didn’t managed to escape or find a cure.  
The crystallization.  
Is now eight long years she undergoes painful practices to eliminate crystals that are forming on her, both outside and inside.  
Now she has only two options: find an unlikely cure … or find an heir who is not (and will not be) afflicted by the disease.
 
The Crown:
 
Created after the first War of Subversion, the crown was forged by Nova herself, after killing a powerful dragon of the resistance, which she considered an “old friend”, and dug him his teeth.  
The crown is full of a powerful and unknown dark energy, defined by the mysterious scholar Haerus Memorae, the first and only one to have stolen the crown, in his notes as “pure evil coming from the depths of the Other World.”  
Few know what this means.
 
The Cutie Mark:
 
Transmuted after the princess of friendship had give up to the use and the power of the dark arts ( used in principle to defeat a powerful necromancer ), it should represent the explosion of a star, that is turning into a black hole.