Now Eight Rules, too, had the six-and-thirty transformations, and there before the steps he made a show of his arts: pinching his fingers in a spell and reciting a charm, he gave a shout — 'Grow!' — and, with a bow of his waist, shot up to a height of eight or nine zhàng, for all the world like a road-clearing god.

He has 三十六般變化, thirty-six transformations — exactly half his brother's seventy-two, a scorecard the novel never states outright and never lets you forget. 捻訣念咒 is pinching the fingers into a hand-sign and reciting the spell. Watch the two readings of one character in 就長有八九丈長: the first 長 is zhǎng, to grow, the second is cháng, in length; and 丈 (zhàng) is the unit of length, ten 尺 (chǐ). The 開路神, the "road-opening god," was the towering effigy carried at the head of a funeral procession to clear the way of spirits — think of the giant balloon figure at the front of a parade, and then imagine it turning up in a throne room.

So frightened were the two files of officials, civil and military, that they shook and trembled, and the whole court, king and ministers alike, stood stupefied and aghast.

嚇得 (得 = de) is "frightened to the point that"; 戰戰兢兢, shaking and trembling, is still the standard idiom for terrified caution. 呆呆掙掙 is a rougher doubled phrase for a whole room staring blankly. The court is now as frightened of its rescuer as it would be of the demon.

Just then a hall-guarding general asked, 'Elder, if you can grow so tall as this, to what point must you grow before you reach your limit?'

The 鎮殿將軍 (將 = jiàng), the general on duty in the hall, asks a technical question in perfectly good faith. 變得 (得 = de) 身高 is "transformed so as to be tall"; 長到 (長 = zhǎng) is to grow to a point; 甚麼去處 (甚 = shén) is "what place." He is the straight man, and he does not know it yet.

The blockhead came out with another of his blockish remarks: 'That depends on the wind. An east wind is bearable, a west wind will do; but if a south wind should rise, I'd butt a great hole right through the blue sky.'

The narrator flags it in advance — another piece of 獃話, blockhead-talk — and then Eight Rules delivers. 看風 is "depends on the wind"; 西風也將就 (將 = jiāng, 將就 = to make do) is "a west wind will pass"; and 拱個大窟窿 is to butt out a great hole. He has answered a sober enquiry about the limits of his magic by threatening to put a hole in the sky.

The king cried out in alarm, 'Put away your magic power! I see now what your transformations are.' Eight Rules gave himself a shake downward, resumed his true form as before, and stood in attendance before the steps.

收了神通 is "put the magic away"; 曉得 (得 = de) is "I see, I get it" — the king has seen quite enough. 把身一矬 is to give the body a downward shrink. And 現了本相 takes 相 as xiàng, form or appearance, which is a different word from the xiāng of 相見 and 相請 earlier in the chapter — same character, two jobs. 本相, "original form," is a loaded phrase in a novel where nearly every creature has one it would rather you did not see.