水泄不通 Not A Drop Could Leak Through
那魔王闖入洞裡,閉門不出。概眾把一座翠雲山圍得水泄不通。那魔王闯入洞里,闭门不出。概众把一座翠云山围得水泄不通。
逐句解 Line by line
The Demon King rushed into the cave and shut the door and would not come out.
The second time in this chapter that the Bull King has ended a fight by shutting a door — the previous one closed at 緊閉了洞門不題 in exactly the same posture.
The whole company ringed Emerald Cloud Mountain about so that not a drop could leak through.
水泄不通, "not a drop could leak through", is the set phrase for a cordon so tight that water could not get out, and it marks the change in the chapter's situation: the Bull King is no longer being chased but besieged. 圍得 takes the light linking de, hooking the encircling to its result.
閉門不出 for the second time in the chapter. The Bull King ended the fight at the Cloud-Touching Cave the same way, and the repetition marks how little has changed: he still has the fan, and he is still behind a door.
What has changed is outside it. 水泄不通 — a cordon so tight that water could not get out — and the situation is no longer a chase but a siege. The chapter has been converging on this since the local god first blocked his retreat in an open field.