DelzGB

Within the virtual world of “Avalon Online”, Finn, or otherwise known as “Echo” within the game, was one of its greatest players. After logging off from a long session, however, he notices something awry outside of his apartment. 
The streets were flooded with chaos, screams echo through the night, and hell is loot loose. Monsters from Avalon Online are running through the streets, wrecking havoc. In the midst of this hellish awakening, Finn is greeted with the one gift bestowed to humanity in this dark hour:
[...Assessing life experience…] 
[Assessment Complete] 
[Name: Finn Thorne] 
[Age: 20] 
[Designated Class: Assassin] 
[Starting Level: 5] 
[A [Legacy System] has been bestowed to you for your accomplishments within Avalon.]
[Assimilation System Awakened.] 
In this twisted turn, as the world as it was once known is gone with the arrival of magic and monsters, the remnants of humanity must level up if they wish to survive. 
Finn is left in this dark, hopeless apocalypse, using his own experience from Avalon Online to best survive what seems to be an impossible task.

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Level-Up Apocalypse: Surviving With The Assimilation System

The morphing, dragon-shaped entity shifted again, changing its flesh into yet another figure. To inspire, the pressure in the crater felt lessened as he watched the being morph.

[Gravitational levels normalized in area | Adjusting output.]

"The gravity—?" Charlotte questioned.

"Wait, there's no more disturbance then—" Finn realized, looking up.

The sound of air humming was clear as day before witnessing multiple, high-speed objects descending through the sky.

"Radegasts!" Charlotte called out.

Just as the girl had announced their arrival, a squadron of the mechanical giants landed around the crater. It was a relieving sight, seeing some of which were designed differently; a red, more gnarly unit, and even one slightly larger with cannons mounted on its shoulders.

"Hey!" A harsh, feminine voice emitted from the scarlet mech, undoubtedly addressing the two. "Stay clear! The Bloodrider Squadron will handle this!"

All-Out Attack