User blog comment:Dodo8/About Unique Dragons and Dragon Spells/Potions/@comment-5328906-20120821200102

not even the 50/50 doens't seem to be the case, there also seems to be pattern. Each week the first (3 the first week and 4 the second) awarded book/potion and then poof... 7 fails and almost 6 fails... the mechanics have indeed improve but lets see if they keep improving and new dragons come