Since the discussion died down, I have something new for everyone now
I recently started modding xtended and I made some relatively simple changes to the Aos Si to make the leaders really feel different to each other and to make the winter court viable. The changes:
-Larincsindhe is now phil/enlightened. This allows him to flexibly jump from winter court to summer court. Phil makes the winter court very strong since without the need for food you can employ a lot of specialists. However, without a way to grow, Larincsindhe still needs to regularly switch back to the summer court, but doesn't get punished for doing so thanks to enlightened.
-Cairn is now char/hunt. Hunter is a new trait I made specifically for him that gives a slight fighting buff to recon units and more importantly allows you to capture slaves for 50 mana which can be sacrificed for another 50 mana (the cost is still up for revision, but 100 mana for one pop seems good so far) to increase the population of a city by one. This uniquely allows Cairn to permanently stay in the winter court civic and gives him general some unique play(basically mana takes the role of food for him, and you need to aggressively capture slaves a lot if you want decently sized cities). it also gives him some interesting synergy with the slavery tech; While the slavery civic is unappealing for him, being able to get slaves without the need to pay mana is worth a lot to him. Char is also half a military trait, has decent synergy with winter court and just seemed more fitting to a faerie than aggressive.
Overall, together with the winter court changes, this makes Cairn a very frightening military leader, without being too bad in the economic department(while his normal kit imo makes him very one-dimensional).
-Crom stays the same as usual. He is very good while simply playing summer court and I want him to stay that way.
-Winter court:
-no extra maintenance
-no extra military
-no extra production: extra maintenance is very punishing so it had to go, while extra military and extra production seemed actually unnecessary/over the top, together with the other changes
-fishing boats +2 hammers +2 gold: Originally I wanted to give just +1 hammer +1 gold for ALL water tiles, but after playtesting I'm actually fine with this. This still makes being at the coast uniquely appealing if you want to be in winter court a lot, while the summer court prefers inland.
-winter faerie race gets no -15% strength penalty: It just seemed weird to me that the summer faerie race was actually stronger than the winter faerie race since it gives extra healing. Now the winter faerie race is actually stronger in fighting, but still lacks the extra healing.
Water Magic:
-Riches of the Sea now adds Ressources instead of gold.
-Gravity moved to water magic instead of nature
Both these changes imo were necessary to make water magic a bit more appealing in comparison to nature magic, which imo still is significantly stronger than everything else especially for faeries, but not by such a huge margin anymore. Being able to create land also just fits water magic civs infinitely better than nature magic civs because it allows you to fix bad coastlines, which are otherwise quite punishing for water-based civs.
Todo:- I still think about adding some kind of damaging/weakening aura to the winter court realm instead of the fighting "buff". But the winter court is unique enough right now, so it's imo not necessary.
- Mind magic is still pretty odd for the faeries and even less useful than water, but on the other hand, Larincsindhe is very strong in terms of traits now anyway.
- I'm also still not sure if Cairn should have phil instead of Larincsidhe since he's the "winter court guy". On the other hand, without phil Larincsidhe doesn't have much reason to change into the winter court except in war times, so giving phil to Larincsidhe instead seems like the better way to handle things.
Please discuss these changes. On Calaventes remark, I also realized that the different court civics are the "core mechanic" of the faeries, so I tried to focus on that instead of bringing in new stuff like winter/summer cities. I playtested these changes quite a bit and to me they seem to accomplish what I want. I also really like that unexpectedly, empyrean is now also a viable religion choice for faeries that aren't crom, because liberty + winter court is great.