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

As Mark deactivated the skill, the pressure was lifted from the surroundings and the spectators started taking deep breaths after feeling helpless for 20 seconds straight.

The lower realm cultivators were staring fearfully at Mark while the higher realm cultivators were staring angrily, feeling humiliated.

Lai Peng quickly rose to his feet and flew toward the battle platform. He landed beside the decapitated disciple of his sect and looked at Mark with reddened eyes. "You bast*rd, I'll kill you…"

"Hmpf, you should have expected this when you planted a spy in the Kunlun sect and dared to ambush them on the way, killing three of them in the process," calmly replied Mark.

The Grand Elder of the Kunlun sect who also came as a guest couldn't help but clench his fist in anger. He wanted to go there and attack Lai Peng but according to his sect master's orders, he cannot do that.

Leaving for the next destination, the Kunlun mountains.