身外身法 The Hair-Clone Host
這老魔與大聖戰經二十回合，不分勝負。他把那劍梢一指，叫聲：「小妖齊來。」那三百餘精一齊擁上，把行者圍在垓心。好大聖，公然無懼，使一條棒，左衝右撞，後抵前遮。那小妖都有手段，越打越上，一似綿絮纏身，摟腰扯腿，莫肯退後。大聖慌了，即使個身外身法，將左脅下毫毛拔了一把，嚼碎噴去，喝聲叫：「變！」一根根都變做行者。你看他長的使棒，短的掄拳，再小的沒處下手，抱著孤拐啃觔，把那小妖都打得星落雲散，齊聲喊道：「大王啊，事不諧矣，難矣乎哉！滿地盈山，皆是孫行者了。」被這身外法把群妖打退，止撇得老魔圍困中間，趕得東奔西走，出路無門。这老魔与大圣战经二十回合，不分胜负。他把那剑梢一指，叫声：「小妖齐来。」那三百余精一齐拥上，把行者围在垓心。好大圣，公然无惧，使一条棒，左冲右撞，后抵前遮。那小妖都有手段，越打越上，一似绵絮缠身，搂腰扯腿，莫肯退后。大圣慌了，即使个身外身法，将左胁下毫毛拔了一把，嚼碎喷去，喝声叫：「变！」一根根都变做行者。你看他长的使棒，短的抡拳，再小的没处下手，抱著孤拐啃觔，把那小妖都打得星落云散，齐声喊道：「大王啊，事不谐矣，难矣乎哉！满地盈山，皆是孙行者了。」被这身外法把群妖打退，止撇得老魔围困中间，赶得东奔西走，出路无门。
逐句解 Line by line
The old fiend and the Great Sage had fought some twenty bouts, with neither the advantage.
不分勝負 — "no telling win from loss," 分 read fēn, "to distinguish"; the single combat is a deadlock.
He gave a point of his sword-tip and cried: “Little ones, all together!”
劍梢一指 — "pointed with the sword-tip." Unable to win singly, the fiend calls up his host.
The three hundred and more sprites swarmed up in a body and ringed Pilgrim in their midst.
垓心 (gāi xīn) — "the very center [of the ring]." The imps enclose Wukong on every side.
That fine Great Sage, wholly without fear, plied a single staff — thrusting left, striking right, guarding rear and front.
公然無懼 — "openly, utterly unafraid." The string of paired verbs (左衝右撞，後抵前遮) renders the blur of his defense.
Those little fiends all had their skill: the more he beat them the more they pressed on, clinging like cotton-wadding to his body, clutching his waist and dragging at his legs, not one willing to fall back.
一似綿絮纏身 — "clung like cotton-floss to the body," a vivid figure for the imps’ smothering numbers; 摟腰扯腿, "clutching his waist and pulling his legs."
The Great Sage grew flustered, and at once worked his Body-Beyond-the-Body art: he plucked a fistful of hairs from under his left flank, chewed them small and spat them out, and cried: “Change!”
身外身法 (shēnwài-shēn fǎ) — the "body-outside-the-body" method, Wukong’s signature trick of turning plucked hairs into copies of himself. 喃碎噴去, "chewed them fine and spat them forth"; 喝 (hè), to shout.
Every single hair turned into a Pilgrim.
一根根都變做行者 — "each and every one became a Pilgrim." The multiplied Wukongs overwhelm the swarm.
See them: the tall ones wielding staves, the short ones swinging fists, and the smallest, with no room to strike, seizing the imps by the hip-bone and gnawing their sinews — they beat those little fiends into a scatter of falling stars and drifting cloud, till the imps cried out as one: “Great King! The thing has gone all awry — hard, hard indeed!”
長的使棒 — "the tall ones," 長 read cháng ("long, tall," against 短 "short"), not zhǎng. 沒處下手, "no place to start," 處 read chù; 抱著孤拐啼觔, "clutching the hip-bone, gnawing sinew," 著 durative (zhe). 難矣乎哉 (nán yǐ hū zāi), "how hard indeed!", 難 read nán, "difficult."
Covering the ground and filling the hills, they were all Sun Xingzhe.
滿地盈山 — "carpeting the earth, brimming the mountain": the comic image of a whole landscape of identical Monkeys.
The Body-Beyond method drove the pack of fiends back, leaving only the old fiend hemmed in the midst, chased east and west with no road out.
止撇得 (zhǐ piē de) — "left only," 得 the complement de. 圍困中間 (wéikùn zhōngjiān), "hemmed in the midst"; the fiend is now isolated and cornered.
The mass battle is the chapter’s great comic set-piece. Deadlocked in single combat, the fiend throws his three hundred imps at Wukong, who is smothered — the wonderful figure has them "clinging like cotton-floss," clutching his waist and dragging his legs. His answer is the 身外身法, the hair-clone trick: a fistful of hairs, chewed and spat, becomes a whole army of Monkeys.
The humor turns visual and cumulative — tall clones with staves, short ones with fists, the smallest gnawing the imps’ sinews — until the fiends are beaten to "a scatter of falling stars" and the ground and hills are "all Sun Xingzhe." The trick both routs the host and isolates its master: the old fiend is left hemmed in the midst, cornered, and ripe for the desperate resort to the Plantain Fan that follows.