The Cossacks, a new expansion of Europa Universalis IV, will introduce the Estate system that allows you to assign control of your provinces to local factions - priests, nobles, or even Cossacks - sacrificing some income in the name of lower unrest, more manpower or cheaper cavalry. You must keep an eye these Estates, though - if they get too strong, they may make a move on your throne. If they feel neglected, they may interfere with efficient governance.
Other features include new diplomatic options, native policies, improved espionage, and more.
Europa Universalis IV: The Cossacks is coming to digital retailers and the Paradox store on December 1st.