Perhaps it's a matter of self - defense in the guy's mind. He might feel threatened by the man he trapped and thinks that this is the only way to keep himself safe. But his sense of self - defense is extreme and unethical. He may have misinterpreted the man's actions as more dangerous than they actually were.
Well, one possible motive could be revenge. Maybe the guy has some sort of grudge against the man he trapped. Another could be that he's trying to gain something, like information or valuables. For example, if the man trapped has some secret knowledge, the trapper might be trying to force it out of him.
It could be that the guy trapping the man is just plain crazy. He might not have a rational motive at all. He could be acting on some delusion or impulse that makes him think trapping the man behind the wall is a good idea. Maybe he heard voices in his head telling him to do it.
Chapter 341, "Moao's Nine Towns, the Inspection System and Zhenyu, Li Hu and Hong Yuru", is the clearest early answer because it turns Beining Mountain's situation into a concrete plot event. The setup is The entire Moao Mountain Range stretches from northwest to southeast., but the pressure keeps building through Though it is situated northeast of Beining Mountain, from the....
Chapter 328, "Unexplainable Unease, Jade Dew Stone, Li Xuanling's Panic (Part 2)", is the clearest early answer because it turns White Dew Gu's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Through the harvest after killing Wu Xiong and Li Xuantian, Xia Hong... and follows through with The rain of two thousand iron arrows was nothing compared to the four....
Chapter 172, "Shang Shaojing is Here Too?!", is the clearest early answer because it turns Wen Jia's situation into a concrete plot event.
Chapter 135, "Lai Fu is Missing!", is the clearest early answer because it turns Lu Xingchao's situation into a concrete plot event. The chapter turns that into something concrete by moving from The sun blazed down mercilessly, but thankfully, the path to the...
Chapter 327, "Beast Tide Showdown, the Wolf King’s Gambit, and White Dew Gu’s Last Stand", is the clearest early answer because it turns Thunder Kui's situation into a concrete plot event. The setup is The thunderous roar came from the flanks of the depression., but the pressure keeps building through Xia Hong caught it from the corner of his eye, and his previously....
Chapter 326, "Divide and Annihilate, Shattering Divine Light—The Trump Card Arrives! (3)", is the clearest early answer because it pushes Striped Tiger into a new phase or setting. A useful checkpoint is the way the scene starts with Despite being restored to its normal size, the surface of the Striped... and follows through with Coming so late, it seems they were waiting for the right moment,....
Chapter 307, "Silver Mine News, Uprisings Everywhere (Part 3)", is the clearest early answer because it turns Hou Jing's situation into a concrete plot event. The setup is Wu Tianxing hastily cupped his hands and replied, "This time it's in..., but the pressure keeps building through The main culprit is surnamed Song, called Song Ning, a nephew of Song....
Chapter 53, "Save People!", is the clearest early answer because it turns Life Plate's situation into a concrete plot event. It opens with Night had fallen over Chixia Village, eerily void of any human sounds. and closes on Wait, did this kid accidentally fall into the water?] [Help, this....
Chapter 209, "Given by Me", is the clearest early answer because it turns Lili's situation into a concrete plot event. A useful checkpoint is the way the scene starts with He Yun suddenly spilled out over a dozen cards.
Chapter 332, "Chen Ying's New Discovery, Xia Yuning, Good News Abounds", is the clearest early answer because it turns Xia Yuzong's situation into a concrete plot event. A useful checkpoint is the way the scene starts with Li Xuanling was about to speak when Xia Hong's voice suddenly came... and follows through with Xiao Ning, and even Xiao Yu, who was lying in bed in the room, looked....