荥泽 / Xingze
荥泽 / Xingze enters the wiki through 《资治通鉴·秦纪》103-1｜司马迁看中的信陵君算是小人吗？ as the water-control point southeast of 管城. The episode says 秦国 already controls Xingze when 信陵君 considers the next step after defeating 蒙敖.
The source uses Xingze to explain why 大梁 remains in danger even after the coalition victory. Control of water near the Wei capital could let Qin threaten flooding or hydraulic pressure, and the host compares this danger with the earlier 智瑶 attempt to flood Jinyang.