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Slavic Reformation

This mod just adds 4 extra flavours for slavic pagans: Slavic Polygamy+, Slavic subjucation cb, Slavic Feudal Government and Bloodlines of the three brothers

Slavic polygamy+
Slavic pagan faith now can have 7 concubines. When going reformation, Children of Perun reform Doctrine now grants you 8 wives, incompatible with base polygamy reform doctrine since it only enables 4 wives (reformation will be blocked if you select both doctrines together). This is based on Vladimir the Great and his seven wives when he was still pagan before converting to Orthodox Christianity https://en.wikipedia.org/wiki/Vladimir_the_Great

Slavic Subjucation cb
A new subjucation cb for unreformed slavs for King/Emperor tier characters, provides an alternation to the usual one life subjucation cb outside of become king ambition. Only enabled against fellow unreformed slavic pagan lords to avoid being op. Cb will be voided once religion is reformed, unless you remain of the older faith (essentially this makes conquering fellow slavs a lot easier before reformation)

Slavic Feudal Government
A new feudal government for reformed Slavs that replaces the default feudalism government, adds a blend of tribal and feudal government. You get some increase in demense & vassal limit, and you can call tribal vassals, feudal vassals and fellow Slav Feudal vassals in all your wars. Revocation of tier titles below emperor are free. Vassal retraction also free.

Bloodlines of the three brothers
Say hello to the three mythological brothers: Lech, Czech and Rus. Certain characters will get their bloodlines

Extra
Hitting the Slavic Union decision button now causes Slavic Union Empire to assimilate all other active vassal king tier titles upon creation

Highly recommended to play with Orrie's 4, 6 and 9 reform doctrine mods.

Unfortunately, this mod is a bit effy when played with byzsla's Better Slavic Pagan Mod (awesome mod btw, go check it out) due to reformation clashes. But if you still want to play with both mods, you will have to tie some files together.
My current recommendation would be to unpack the Slavic Reformation mod zip, delete this folder: common/religion. Open Slavic Reformation.mod with either text edit or notepad, change the path
from
path="mod/Slavic Reformation.zip"
to
path="mod/Slavic Reformation"
This will unfortunately remove the unreformed 7 concubine feature, but you will still get 8 wives after reformation

Have fun!

P.s. In case steam messes with the download (in which it is notorious for)
Step 1: Go to Documents/Pandorax Interactive/Crusader Kings 2/mod
Step 2: Locate Slavic Reformation.mod.mod
Step 3: rename Slavic Reformation.mod.mod to Slavic Reformation.mod
Step 4: start the game, check the mod in the mod tab and play