“I love me some good body horror” - Cosmos.  
“I need a body, A physical body, To truly cement my presence in this world”“But not just any body. Not a host body. I will not possess somebody like some ghost. I shall not remain but a spirit in someone else’s shell.  
“Not that any of these weak prissy pony pissy princesses could hold even a fifth of my true self!”  
A light bulb appeared in her mind. Then it grew teeth and ate the cat of doubt.
 
“I crave A body of my own! And like a true Draconequus - I shall be made from only the best parts.”“I shall take their best and strongest, their leaders and heroes. And from their flesh i shall craft myself a new form - The body of a true goddess!”  
“Their every cell shall be corrupted beyond recognition! Every molecule filled with my chaos until it bursts and reforms to my liking!”  
“The very minds and souls shall be torn apart and reformed into mine. Their magic shall be tainted with my might! Their powers shall become my power, Twisted Chaotic!  
“Their very essence warped into a single whole as I complete my ascension! And through this I shall reach a power worthy of my new self!”  
“Not merely a Lord of chaos, but a goddess of the Sun and the Moon, Of love and life and land and friendship and magic itself!  
“I will be the undisputer ruler of all that is and ever will be!”  
“I will be a whole, greater than the sum of their parts! For there will be no parts!”  
“There will be no part of your friends living on deep inside me!”“There will be no Celestia, Luna, Twilight, Cadence, Starlight, Trixie, Zecora or Princess Big Mac”  
“There will be only…”  
(pause for deep breath)  
“COSMOS!”
 
(Yes - this actually happened in the comic - I just took the visualisation a little further)