There is actually a bio for Zuo Ci in the Later Han Book
Hou Han Shu.
後漢書 卷八十二上方術列傳第七十二下
左慈字元放，廬江人也。少有神道。嘗在司空曹操坐，操從容顧眾賓曰：「今日高會，珍羞略備，所少吳松江鱸魚耳。」〔一〕放於下坐應曰：「此可得也。」因求銅貯水，以竹竿餌釣於盤中，須臾引一鱸魚出。操大拊掌笑，會者皆驚。操曰：「一魚不周坐席，可更得乎？」放乃更餌鉤沈之，須臾復引出，皆長三尺餘，生鮮可愛。操使目前鱠之，周浹會者。操又謂曰：「既已得魚，恨無蜀中生薑耳。」放曰：「亦可得也。」操恐其近即所取，因曰：「吾前遣人到蜀買錦，可過敕使者，增市二端。」語頃，即得薑還，并獲操使報命。後操使蜀反，驗問增錦之狀及時日早晚，若符契焉。
〔一〕松江在今蘇州東南，首受太湖。神仙傳云：「松江出好鱸魚，味異它處。」
後操出近郊，士大夫從者百許人，慈乃為齎酒一升，脯一斤，手自斟酌，百官莫不醉飽。操怪之，使尋其故，行視諸鑪，悉亡其酒脯矣。〔一〕操懷不喜，〔二〕因坐上收欲殺之，慈乃卻入壁中，霍然不知所在。或見於市者，又捕之，而市人皆變形與慈同，莫知誰是。後人逢慈於陽城山頭，因復逐之，遂入走羊群。操知不可得，乃令就羊中告之曰：「不復相殺，本試君術耳。」忽有一老羝屈前兩膝，人立而言曰：「遽如許。」〔三〕即競往赴之，而群羊數百皆變為羝，並屈前膝人立，云「遽如許」，遂莫知所取焉。〔四〕
〔一〕鑪，酒肆也。
〔二〕喜音許吏反。
〔三〕言何遽如許為事。
〔四〕魏文帝典論論郤儉等事曰「潁川郤儉能辟穀，餌伏苓，甘陵甘始名善行氣，老有少容，廬江左慈知補導之術，並為軍吏。初，儉至之所，伏苓價暴貴數倍。議郎安平李覃學其辟穀，食伏苓，飲寒水，水寒中泄利，殆至殞命。後始來，眾人無不鴟視狼顧，呼吸吐納。軍祭酒弘農董芬為之過差，氣閉不通，良久乃蘇。左慈到，又競受其補導之術。至寺人嚴峻往從問受，奄豎真無事於斯術也。人之逐聲，乃至於是」也。
Hou Han Shu Chapter 82 (Legends Chapter 72 part 2 - Legends of Special Skills)
Zuo Ci, style-named Yuanfang, was from Lu Jiang. He acquired the "Way of the Immortals" when he was young. He was a guest of Sikong (the Minister of Works), Cao Cao. Cao Cao calmly said to all the guests, "In today's banquet, many delicacies were prepared, except lacking some perches from Song Jiang (River Song)."
(1) Fang replied from his seat, "It could be obtained." He asked for a bronze tray filled with water, and used a bamboo stick as a fishing rod to fish inside the tray. A moment pasted, he pulled out a perch from the tray. Everyone was stunned. Cao Cao clapped his hands and laughed, "One fish alone is not enough for everyone in this table, is there more?" Fang then changed the bait and dropped it. Moments later, the perches just kept coming. They were all three feet long, fresh and lovely. Cao Cao had it cut up into thin slices before him and have it passed around. Cao Cao then said, "We got the fish, only if we could also have some fresh ginger from Shu." Fang Said, "It could also be obtained." Cao Cao feared that Zuo Ci might get the ginger from nearby, so Cao Cao said to Zhu Ci, "I ordered an emissary to buy some brocade from Shu earlier, you can go after the emissary and order him to buy an additional two duans
(I) of brocade." Just a moment after Cao Cao finished talking, Zuo Ci brought back the ginger and a message from the emissary. Afterwards, when the emissory came back from Shu, Cao Cao examined the emissory and asked questions about the form of the added brocade and the time and date, it seemed to coincide.
(1) Song Jiang (River Song) is located at the Southeast of Suzhou, originated from Tai Hu (Lake Tai). The
Legend of the Immortals stated, "Song Jiang produces very good quality perches, the taste of them is different from anywhere else."
(I) A "duan" is a measurement of length of fabric.
Cao Cao traveled to the near suburb later, along with a hundred or so literary intelligentsia. Ci prepared a pint of wine, a catty of meat, and he served them personally. Everyone of the hundred or so literary intelligentsia were both drunk and full. Cao Cao was suspicious. He was searching for the cause, taking a look at every wineshop, all the wine and meat were gone from all the stores. Cao Cao was not pleased at all. So he had him arrested at the banquet, and wanted to kill him. Ci hid inside a wall, suddenly disappered without a trace. He was perhaps seen in the market. Cao Cao tried to capture him again, but then the appearance of everyone in the market transformed to look like Zuo Ci. No one knew who the real Zuo Ci was. Later, Zuo Ci was found again on the hilltop of Yang Cheng, he was being pursued by Cao Cao again. Zuo Ci went hiding into a flock of sheeps. Cao Cao knew Zuo Ci could not be captured, he commanded in the middle of the flock, "You will not be killed, it was just a test on your skills." Then an old ram standed up like a person, bent its two front knees, and said, "
something something"(遽如許-言何遽如許為事). Imediately, Cao Cao went towards it, albeit with a struggle. But then the whole flock of several hundred sheeps transformed into rams, standed up bending both front knees and said,
"something something again" (遽如許). Thus, it could not be decided on which one to be captured.
(1)
(1) (is the Dian Lun stuff, some of them are translated several post above this one, I will try to translate this later if it hasn't been already done so...)
Please feel free to edit, correct, or change anything, as they are not very well done. Any help is greatly appreciated. Thanks in advance!
And I actually managed to finish most of them... what's better to do in a Friday night then translating! Right ?
). It also mentioned his skills were very hard to aquired, needed to work very hard at it, or else it would be life threatening... 
It's hilarious that the eunuch went and tried to learn from him...
羝 ?
(We were having prospective graduate students visiting our program, and so we had to socialize with them, etc... there's more of it today so I just got home and I'm not any more sober than when I posted last night, heh. How I'll get real work done by Monday I don't know.)