My plan to ensnare Prussia is as follows: I will make use of the current military access to march my armies through their lands to take control of Denmark. I am beginning to side with Austria due to my buying out of their region several turns prior to my current one (the victory condition one) which means I don't have to go to war with them to win, whereas with Prussia I need two of their regions (both of which are rich regions) so my coin means nothing After this set of conflicts I will have to choose between Prussia and Austria. Austria has gone to war with Denmark and Prussia has gone to war with Mecklenburg and they have both asked me to participate, while they have both broken their alliance with the other. I have started to build forts along the sea and garrison appropriately. I suspect they will invade either my Spanish territories or right along the channel between France and England. It started out by Great Britain breaking my alliance. However my allies have started to turn against each other. With France and Spain now out of the picture I am the strongest Empire. In my campaign now I have control over all of France's previous territories as well as Spain's and Italy as far as Rome (wonder how Catholics feel about the Unorthodox taking over Rome ).
By the time I swept them I was close enough to Kutusov to reinforce him and start pushing the French back.
I sent Kutusov to the front (around Prague) and helped defend my allies there via ambushing merging armies near the border forests while my main force conquored the Ottoman Empire.