The Third War
During the third war, Sylabelle was powerless to help. She saw her family and loved ones perish in the war. Enlisting herself and picking up a weapon, she joined the fray. Only to achieve nothing.

 
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Exile from Silvermoon
A blood elf magister, Umbric, was determined that the sin'dorei would never fall prey to their enemies again. Sylabelle, -having nothing left- followed him. Convinced that the void was essential to the defense of Silvermoon, Umbric and his followers delved into it. Eventually, Rommath had them banished, reasoning that any who treat with the void pose a danger to the Sunwell, and Umbric led his followers south to the Ghostlands to pursue their research. He made a breakthrough after discovering notes left by Dar'Khan Drathir, one of Quel'Thalas' most vile traitors, who had sought the power of the void long before selling his people to Arthas. While Drathir had not succeeded in his endeavor, eventually abandoning his research after a failed attempt to reach a void-infused rift world supposedly containing an item of great power, Umbric — who only now conceded that Rommath may have been right to oppose this course of study — was able to build upon Drathir's findings and open the way to the rift.
 
With his followers, Umbric traveled to the void world now known as Telogrus Rift, which had been destroyed long ago by a being of great power (possibly Sargeras himself). But the fragmented world endured, heavily bathed in the void's energies. Umbric, at last, had found what he was looking for: an ancient and powerful cube that could grant its masters control over shadows.
 
Convergence of shadows
Umbric's followers had dispersed around Telogrus and were intent on uncovering its secrets. Umbric himself was honored to make Alleria's acquaintance, and had learned much of her ordeal on Argus and the shadows she'd consumed. But while Silvermoon's leaders looked upon this occurrence with suspicion and mistrust, seeing only a potential threat to Quel'Thalas, Umbric was of a mind with Alleria, and firmly believed that the void could be controlled and made a force for good. Alleria accompanied Umbric to the site of the cube and cautioned him to be wary as he began the ritual to unlock its power.
 
At that moment, the cube opened with an explosion, allowing Nether-Prince Durzaan — the corrupt ethereal who had stalked Alleria and made an attempt to claim the Sunwell — to surge into Telogrus. Durzaan immediately began a spell to capture and corrupt Umbric and his followers, binding them in an attempt to transform the elves into creatures of the void. Alleria, swearing to save her brothers and sisters, fought a brutal battle to free Umbric and slay the Nether-Prince. Displaying her fortitude, neither Durzaan's power nor his offers to share it were enough to sway Alleria's resolve, as she made clear to Umbric that the whispers are not to be trusted. Alleria succeeded in killing Durzaan, and while their minds and souls were still their own, the sin'dorei had been transformed by the ritual: now, having consumed the void as Alleria had, they had achieved new powers as well as a dangerous susceptibility to its whispers. Alleria immediately offered her aid, wanting to help her transformed kin understand and control their new forms and powers; and Umbric, apologizing for his arrogance, happily accepted. Since Umbric felt that Silvermoon had turned its back on him and his people long ago, Umbric and the void elves swore their allegiance to Alleria and the Alliance.
 
Alleria and Umbric became the first to embrace a new identity: the void elves, ren'dorei in their native tongue — children of the void.
 
Within the void
Sylabelle did everything in her power to master the void and harness it as her weapon. With such power came also its will. Excelling beyond many of the other followers, she became capable of channeling the void into destructive spells. However, Umbric and his followers were worried for Sylabelle's obsession and well-being.
 
The 7th Legion
Now connected with the Alliance, many void-elves wished to help as part of the 7th legion. Sylabelle, who sought to become powerful enough to help also volunteered.
 
As a foot soldier, Sylabelle was assigned to Yalu's squad.
 
Ny'alotha
Syriza went on a mission to Ny'alotha where Sylabelle grew immensely powerful.
In an attempt to stop Vexonia from unleashing a stolen bronze Dragonflight device that could rewind time, Sylabelle dueled Vexiona in the skies of Nyalotha, and fell deep into madness as she did so. Sylabelle couldn't win. Brightburn blew up the bomb to destroy Vexonia's platform. Sylabelle watched Ny'alotha burn as the wave of disintegration from the carapace approached the edges of Ny'alotha and as last act, saved the survivors from Ny'alotha by throwing them back to Azeroth.

After saving those Sylabelle could, she gave herself up and decided to die. However, an unknown presence in the void chose to save her... Pushing her into the chromatic wave of the bomb instead of dying to the destruction of Ny'alotha. She woke up on the Vindicaar, not sure why the void saved her.