殺出洞門來 Out Through The Cave Door
逐句解 Line by line
Only the old fiend and the Monkey King were left, / and a howling wind came scouring along the ground.
猴王, Monkey King, is his oldest title in the book — what he was before he was anybody's disciple. The poem reaches for it at the moment the cave has emptied of everyone else. 呼呼捲地, howling and rolling along the ground, is wind at the level of the feet rather than overhead, which is the wind of a fight rather than of weather.
Watch them fight their way out of the cave door, / and run straight into Wuneng with his blockhead temper up.
看看 is the storyteller pointing: look now, watch this. It is the last line of the poem and it hands the scene straight to Bajie, which is a proper cliff-hanger. 獃性, blockhead nature, is the novel's fixed term for Bajie's particular way of going wrong, and the reader is being told to expect it before it happens.
Eleven lines of verse end on a joke at the expense of the character who has been standing offstage for the whole battle. The poem does not resolve the fight; it gets the fighters through the door and points at what is waiting.
The last line is also a small structural pleasure. Wukong's plan, three passages ago, was to drive the fiend out to where Bajie was posted. That is precisely what happens — and the novel is about to show that Bajie has spent the entire time doing something else.