Snowstar

Mark is a genius military weapon designer who was kidnapped by a mafia gang after refusing to work for them.
They forced him to design unique weapons for five years, until one day he successfully escaped only to get shot by his trusted comrades.
*Ding! You awakened a weapon system.
When he opened his eyes, he was in a different body and in a different world.
"You want to kill a wild boar without being detected? Forget about bow and arrow. Here, I present you this sniper rifle."
"You want to kill a horde of goblins from the sky? Forget about those flying carpets and brooms. Here, I present you the fighter jet." 
"You want to kill a dragon? Forget about taking the help of the S-class adventure team. Here, I present you a nuclear bomb."
Join Mark Spencer/ Lu Zhen as he brings the whole world to its knees with the help of his weapon system.
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Note: Author isn't born in an English-speaking nation and has no editor either. So, please be understanding if there are any grammatical errors.
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Author's current works: War Online, My Soul Card is a Reaper
Author's other notable works:  The Last Slytherin, The Sharingan Hyuga
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You can also support the Author through Patreon or buy coffee on Ko-fi.com

https://www.patreon.com/snowstar

https://ko-fi.com/snowstar5061

Weapon seller in the world of magic

*Ding! In the event of death, the host will be resurrected by the system. However, it only works if the host dies in this pocket dimension.

*Ding! Since it is the first time, the services are provided for free. The host can enable this feature beforehand by paying extra.

"Tch… avaricious," mumbled Mark before paying attention to the demon walking toward him.

Meanwhile, the three-headed demon with spider legs had its senses working at their peak, trying to understand the place he was at and the strength of the human who appeared.

He also seeks the answers from Mark as the latter is likely to be linked to bringing him to this strange place.

As the system was online and protecting Mark, the demon couldn't sense anything from the person.

Seven Deadly sins (part-1)