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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Weapon seller in the world of magic

Mark nodded, "The same bastard who sent men here in my absence and killed Song Yue's father." His words showed clear hatred for the enemy he intends to destroy.

"What do you mean? Why?" Lin Xue grew confused. She couldn't help but cast a sidelong glance at her best friend, "What sort of enmity does he have with you? And why haven't you done anything so far? You have this powerful general behind you."

This time, Song Yue answered instead of Mark, "He believed that he could not take back Western Yan as long as we supported it. You know Western Yan has a large unexplored ether deposit in its mountains. He probably wants to abduct me and use me to distract Lu Zhen's attention while taking it by force. My father, who was guarding me in the disguise of Black Knight for months, sacrificed his life to protect me in his absence. I… If not for me… sigh…" Song Yue couldn't continue anymore and became silent, knowing that her fiancé would scold her if she blamed herself.

Mark's generosity