BIOGRAPHY - PAGE 2
Across the cosmos, Cassandra made the destruction of Genosha but a first step in her grand scheme of death and chaos. Wrapped in the body of Xavier, Cassandra took control of Lilandra’s
mind, having her order her generals to make war upon their own people. Across the Shi’ar Empire, the imperial battle fleet brought doom to their galactic civilization, though none dared question the empress - none except Lilandra’s loyal advisor, Imperial Sage Araki III. He alone seemed to recognize Xavier as being what he truly was, the anti-self of their ally – his Mummudrai. [New X-Men (1st series) #125]
Not all was going as planned, however, for Cassandra. The Shi’ar Superguardian named G-Type reported that contact had been lost with the Superguardians that had been sent to Earth to cleanse the remaining mutant population of the planet, starting with the X-Men. Further, the two X-Men who had been captured, Cyclops and the team’s newest recruit, the enigmatic Xorn, had escaped. Subsequently attacked by both mutants, as they had been held captive on the same ship, Cassandra decided to activate the ship’s self-destruct and return to the Institute, to finish the job herself.
Meanwhile, at the Institute, the X-Men had been using the intervening weeks to put together what had been transpiring under their noses. Trapped in the body of Cassandra Nova, Xavier had managed to reach out with his mind and animate the comatose Beast, finally able to communicate to his former students his predicament. A subsequent telepathic investigation into Xavier/Cassandra’s mind had revealed to the group Cassandra’s true nature and relationship to Charles. Then, after his recovery, the Beast had determined why they were all experiencing various colds and other ailments - the microscopic Nano-Sentinels, which were now attacking their white blood cells.
Though all sick, tired and semi-delirious, the X-Men had managed to fend back the first wave of Shi’ar Superguardians - knowing full well that Cassandra was returning herself for the final showdown. Refusing defeat, Jean hatched an idea. So far, everything had transpired according to Cassandra’s plan. She had thought it all through, every step of the way on a scale they could hardly imagine. The answer lay in doing something she would not expect of them.
Assistance arrived in the form of the returning Cyclops and Xorn. Using his purported power of healing, Xorn managed to heal the X-Men, informing them that the sentinels in their bloodstream 
were now dead. Now returned to a semblance of their former health, the X-Men prepared for Cassandra.
As before, Cassandra made short work of the X-Men, easily bypassing Wolverine and the Beast, even going so far as to control the minds of the school’s students, having them attack in her place. Making her ways to the bowels of the Institute, Cassandra reentered the Cerebra chamber, intent on using the machine to attack the minds of every remaining mutant on the planet. She had not foreseen, however, how Jean had outmaneuvered her.
Before her departure, Cassandra had infected her previous body - the one in which she left Xavier - with the microscopic Sentinels that had ravaged it. Knowing that she had anticipated them trying to save the body in which Xavier’s mind now inhabited, Jean had done the opposite, allowing it to
die. In an attempt to save Xavier’s consciousness and self, Jean had made room in her own mind and stored them within herself. Upon being cured by Xorn, Jean had used the Cerebra chamber to distribute those memories among all the mutants in the world - the same mutants Cassandra now touched via Cerebra. Finding Charles’ consciousness awaiting her, Cassandra’s own self was expelled from Xavier’s body, leaving her once again formless and hostless living emotional energy.
Vulnerable for the first time, Cassandra desperately needed a new host - which Emma Frost was apparently able and willing to trade. In exchange for the safety of herself and her prize pupils, Emma offered the previous body Cassandra had inhabited - that of Xavier’s “sister.” Scanning the DNA of the body and confirming that it was alive and the real deal, Cassandra accepted, inhabiting the body immediately.
Quickly, however, Cassandra realized that something was amiss. The body was not hers, but was 
in fact the Superguardian called Stuff, a shapeshifting artificial life form, which Emma had programmed to emulate Cassandra’s DNA. Now trapped within the synthetic brain, Cassandra found herself unable to think clearly, as well as being a student within a virtual reality classroom. Her new teachers were a programmed version Charles Xavier and Jean Grey-Summers, which intended to teach Cassandra anew. [New X-Men (1st series) #126]
While Cassandra Nova had been decisively neutralized, the X-Men were cautious and locked her away in a cell in a lower level of the Institute. In time, the X-Men would learn that Xorn was not who he appeared to be. In truth, he was Magneto - or at least someone purporting to be the X-Men’s oldest foe - who was attempting to break the X-Men from within. Using his relationship with these most rejected of mutants, Xorn built a new Brotherhood and eventually laid waste to both the Xavier Institute and much of the isle of Manhattan. Afterward, while sifting through the rubble that was once the Institute, Cyclops and the Beast realized that the force-field cell which had contained Cassandra could have been damaged in the attack. Though they searched, the body of Cassandra Nova was nowhere to be found. [X-Men (2nd series) #155]
Soon after this, the X-Men teams were reshuffled with Cyclops and Emma Frost leading the public-facing, superhero-focused team. The line up of this team was quite similar to the one that originally faced Nova but with the curious exception that Emma insisted on bringing in Kitty Pryde, a woman who historically hated her. After a few missions, a deeply planted psychic Trojan horse was activated in Emma’s brain. At the point that Emma had tricked Nova into entering the Stuff
body, Cassandra had implanted false memories into the former White Queen’s psyche that the two of them had met prior to the decimation of Genosha. It was suggested that Cassandra had personally given Emma her secondary mutation to survive the attack, with the understanding that Emma would owe her a favor down the line.
Under this false assumption, and with Nova’s psychic meddling playing off her survivor's guilt and shame of her villainous past, Emma psychically created a new version of the Hellfire Club. The line-up consisted of Emma herself, Cassandra Nova, Sebastian Shaw, a former student of Emma’s that had died in her arms named Negasonic Teenage Warhead, and a mysterious cloaked figure called Perfection. Each of these psychic projections represented a different aspect of Emma’s guilt or shame and all worked towards the ultimate goal of Cassandra, which was freeing her from the secure container in which the Stuff body had been placed (apparently relocated after the attack).
Towards this end, each of the members targeted and incapacitated members of the team, with the Cassandra Nova projection going after Wolverine and, more importantly, Beast. She reduced Beast to a feral version of his namesake, incapable of forming a cogent counterattack and acting 
on pure instinct. Meanwhile, Wolverine was reverted back to the child he was in the late 1800s, too scared and innocent to do anything but run from the rampaging Beast. However, the crux of the plan centered around psychically persuading Kitty that she had a son who had been taken from her and locked in a containment unit in the basement. Only her phasing powers could pass through the defenses of the container in order to free Cassandra Nova’s slimy “Stuff” body, and Kitty was more than desperate enough to do so in her brainwashed state. At the point that the X-Men recovered from their psychic struggles and pinpointed the Cassandra Nova-induced Emma Frost as the source of their woes, it was almost too late to stop Emma from implanting Nova’s brain patterns into either Kitty or teenage student Armor’s bodies. However, just before this happened, a different attack commenced and everyone (sans Nova) was teleported into space to deal with a new threat. [Astonishing X-Men (3rd series) #12-18]