The blueprints were Li Yao's ultimate goal. Taking the two quests was merely incidental.
Killing wasn't of any interest to him; he wasn't a bloodthirsty madman.
The purpose of pushing the copper sphere was very clear: to create chaos and destruction. As for the players from the Blood Leaf Guild, Li Yao could only say that they were out of luck.
At first, Li Yao had planned to hunt down Trolls, but with players who could kill him in a single shot, he naturally would not choose the highly dangerous Trolls. It wasn't that he couldn't, but simply that it wasn't necessary.
The situation today was the same; they simply couldn't penetrate the armory, completing the first task was difficult enough.
As for the second task, Li Yao didn't dare to confirm if they would sabotage his plan. He gave them a chance to leave, but they unwisely declined.