In Dragon #26 (June 1979), in what may have been the debut of "Giants in the Earth," D&D translations of Jack Vance's Cugel the Clever, Talbot Mundy's Tros of Samothrace, and Wagner's Kane appeared. Here's Kane's stat-block excerpt:
The article goes on to give a brief rundown of Kane's appearance and history. It also notes that Kane may be in disguise when encountered, and that he be on an assassination job. In fact:
"There is an 05% chance that when Kane encounteres a party, he is out to assassinate one party member (at random)."
"Kane's long life has made him whimsical. He may unaccountably befriend a player character (regardless of that character's alignment). Roll Kane's reaction to each party member. A 12, on two 6-sided dice, shows he has befriended a character for 1-100 turns. Kane will not assassinate a friend."
The writer also goes through some contortions to try to fit Kane's behavior to D&D's alignment system. He notes Kane's the "eternal rebel" and that (horrors!) "he's not even true to his alignment" and at any particular time "there is a 10% chance he's acting out of character." The author suggests in these cases that a d8 should be used to determine Kane's alignment at present.
The presentation of Kane is this article caused a bit of controversy. In Dragon Magazine #30, Gary Gygax warned in his "From the Sorcerer's Scroll" column that Kane as presented was too powerful. He suggested that 20th level fighter/16th level magic-user/12th level assassin, was more reasonable for his class abilities, though still on the high side. He promised a closer eye would be kept on future "Giants in the Earth" installments.