Well, I was thinking if you could get a union between Muscovy and Poland-Lithuania(which almost happened and was being discussed a few days ago), with the states remaining in a personal union for most of their history, with Muscovy/Russia doing their thing but never expanding against Poland and instead focusing on Persia/Ottomans/East and settling the borders without violence with Poland, Poland-Lithuania can shew Sweden(big maybe) and take parts of Germany, if it reaches the Sudetenland before Austria can marry it into it's possesion, then Austria topples too. Puppet regimes in Hungary and Romania to block the Ottomans, and Pope support going to Poland before France during the reformation(since Poland in this situation is the uber power over France imo), could result in some wankage. All of Europe is ASB, and tbh, what I just proposed would take so many butterflies that it'd probably be ASB. And to top of the personal union, a succesion crisis occurs in Uber Russia which leads to the King of Poland taking the crown and uniting the two countries into the Great Eurasian Union of Russians, Polishmen, Lithuanians, and Germans(?).