I added a disclaimer to the top of the page. Like a lot of pages in the wiki at this "still under construction" point, this page was copied from older content and hasn't been updated yet for the current state of the game. As best I recall these stats are from v1.09, when the countess had a special rune drop when she was first killed, as a sort of bonus quest reward. In v1.10 and v1.11 she's got a much higher chance to drop a rune every time, but the initial bonus rune is gone, and the quality she drops is much lower.
--[[http://www.diabloii.net/wiki/User:Flux Flux]]