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

https://www.patreon.com/snowstar

Weapon seller in the world of magic

Three days later, somewhere in the mountains of Vitra;

Nearby the shores of a stream, Mark was seen roasting up a fish tied to a stick. Steve and James were sitting not far away and eating roasted fish as they were having a chat.

To not repeat the same mistake as in the past, a day earlier, they hid their truth and simply told him that they were travelers searching for their missing father. Meanwhile, Zan Rong didn't tell him about her relationship with Allen. She merely told him who he was and how they ended up in the Elven world.

As a result, this new Mark somehow trusted them more than he did before. It is also why didn't run away after they caught up with him in the mountain. And his current goal is to get back to his world and reunite with his so-called fiancée.

Singularity