The Legend of Zei the Trickster is a tome found in Act II of Diablo III. It is received in Hidden Camp, after talking to Covetous Shen about the "Case of Mistaken Identity".
It reads as follows:
The people of Xiansai worship fifty-nine gods, but few are more revered than Zei, the exiled trickster god who travels the face of the world, disguised as a humble merchant. Tales of his adventures range from ingenious thefts and practical jokes to more... lurid exploits, none of which I am comfortable recording here. — Abd al-Hazir