User blog comment:Tsi Si Fa/Skyrim Chat/@comment-84.27.182.154-20150328184320/@comment-6881629-20150328190546

You'd be better of asking in the forum than a almost three year old blog posts, but i'm afraid it is randomness the only prerequisite for the Ancient Power quests is getting the chalice make sure you don't have any other get x from x quests in your journal though (just in case the number of them you can have is limited).