With a POD after 1150, prevent Novgorod from consolidating power in the north and later forcing most of former Kievan Rus' into a new confederation with him at the helm.
But please refrain from using a certain baltic pagan tribe escaping the Crusaders wrath, conquering most of Rus', forming a medieval superpower by installing their monarch in Poland and later spreading their dynasty further west. This TL belongs in ASB.