She took the materials for the fire-thunder and with a little redesign, she could create a simple version of a land mine. To her, making land mines wasn't difficult; it was just chemical technology. The real challenge was setting the trap.
When the Blood River Sect Leader's head flew off, he probably saw the ground illuminated by the remaining glow of the fire... besides the exploding mine, there were other mines.
During their battle, she had dodged them several times, likely each time narrowly avoiding the mines she had set herself, luring him step by step into them.
Such scheming was terrifying!
But what was even more terrifying was — she had known early on that he was a eunuch and had known that he would hide Yue Taichu in Baizhang Mountain, using him to lead her there, so she had laid mines in advance to counter the design.
A trap within a trap, a scheme within a scheme.