皂旗之計 The Stratagem of the Black-Eagle Banner
玉帝道：「卿有何助？」哪吒道：「請降旨意，往北天門問真武借皂雕旗，在南天門上一展，把那日月星辰閉了。對面不見人，捉白不見黑，哄那怪道，只說裝了天，以助行者成功。」玉帝聞言：「依卿所奏。」那太子奉旨，前來北天門，見真武，備言前事。那祖師隨將旗付太子。玉帝道：「卿有何助？」哪咤道：「请降旨意，往北天门问真武借皂雕旗，在南天门上一展，把那日月星辰闭了。对面不见人，捉白不见黑，哄那怪道，只说装了天，以助行者成功。」玉帝闻言：「依卿所奏。」那太子奉旨，前来北天门，见真武，备言前事。那祖师随将旗付太子。
逐句解 Line by line
The Jade Emperor said: "What help do you propose?" Nezha said: "Issue a decree, if you please, to go to the Northern Gate and borrow from Zhenwu his black-eagle banner; unfurl it once above the Southern Gate, and it will shut away the sun, moon, and stars.
請降旨意 (qǐng jiàng zhǐ yì), "please hand down a decree," and here 降 is jiàng, "to send down," where Sha Monk's demon-quelling staff took xiáng, "to subdue." 皂雕旗 (zào diāo qí) is the black-eagle banner. 真武 (zhēn wǔ) is Zhenwu, the Perfected Warrior, the great god of the north, whose color is black and whose banner is accordingly the right tool for putting out the sky.
"Face to face, none will see the other; grasping at white, they'll not make out black — and so we'll fool the fiends into thinking the sky is bottled, and help Pilgrim succeed."
對面不見人 (duì miàn bú jiàn rén), "you could not see a man standing in front of you," and 捉白不見黑, catch hold of something white and you still would not make out the black. 哄那怪 (hǒng nà guài), "fool those fiends." Nezha's plan is not to bottle the sky but to counterfeit the effect -- which is precisely what Pilgrim promised, so the two of them are running the same con from opposite ends.
The Jade Emperor, hearing this, said: "Let it be as you propose." The Prince, taking the decree, came to the Northern Gate, met Zhenwu, and laid out the whole matter.
依卿所奏 (yī qīng suǒ zòu), "as my minister has submitted, so be it" -- 卿 is how a sovereign addresses an official, and the whole formula is court boilerplate. 奉旨 (fèng zhǐ), "having received the decree."
The Patriarch thereupon handed the banner to the Prince.
祖師 (zǔ shī), "the Patriarch," is Zhenwu's title. 隨將旗付 (suí jiāng qí fù), "thereupon handed the banner over," 將 doing the work of 把. He asks no questions at all, which is either good discipline or a hint that everyone in Heaven enjoys this sort of thing.
Nezha's plan is elegant: do not bottle the sky, which cannot be done, but counterfeit the result. Zhenwu's black-eagle banner, unfurled over the Southern Gate, will blot out sun, moon and stars, so that two demons standing face to face will not see each other. Plunged into blackness at the exact moment Pilgrim throws his gourd, they will take the darkness for the deed.
The passage completes Heaven's collusion. The Emperor assents, the decree goes out, Zhenwu hands over his banner without a question, and the entire celestial machinery is mobilised to help a monkey cheat two junior demons out of their master's property. The comedy is in the disproportion -- gods and emperors marshalled for a roadside swindle. It also quietly insists on the stakes of the pilgrimage, for which even the sky may be faked.