Leeches is a good idea, rewarding the downtime from cleansing debuffs with extra resources would make it feel way less bad when you are doing mechanics that need to be cleansed.
Rescue trait feels more like fun flavor then anything else, but I've no complaints otherwise.
While I do agree that making Selene and Eos distinct again would be great. I can't help but feel that this model wouldn't encourage healthy play. I can already see all the bad scholars exclusively using Selene at the detriment of the group even if the really good Scholars are swapping them back and forth like bosses. While skill ceiling is absolutely something that should be a thing I can't help but fear this system would just create toxicity. at the bare minimum I would keep Embrace as the filler spam for both faeries so you always have some passive healing going out.
However, all that I said would be contingent on whether or not the actions are shared in their cooldown, if the actions are all seperate then I can see the system working, But i disagree with the offensive fairy having an "auto-attack" because of the situations where a bad scholar would stay exclusively in Selene.
Is there going to be a trade-off of some sort to Aetherpact? Like locking you out of controlling your faerie for X seconds? or is just going to be a toggled on demand powerful regen? That alone sounds too powerful to me.
Since I see no mention of it? is this system going to come with more ways of generating fae guage to offset the fact that more abilities have a cost and that there's more of them you want to use?
No complaints about Seraph, turning it into a powerful mitigation cooldown sounds like a natural progression. If you really wanted to be silly and overkill, have Seraph be an upgrade to Fae Illumination that more or less makes the Seraphic Illumination an "aura" that lasts as long as the Seraph is out.
With Tabula Rasa, i can't help but feel in most cases people would only dissipate Selene, I see no reason for Embrava AND Kaustra to be available regardless of the faerie eaten. especially assuming it's locking you out of both. The spells themselves are fine tho, Kaustra being a free weave slot for the extra aetherflow you have makes it quite solid as an offensive option, and Embrava being a solid emergency heal seems to compliment one another very well.
Attaching the Biolysis spread to Chain feels weird to me. Personally I would attach the spread to Art of War, with Art of War dealing increased potency to the targets afflicted. That way it's more readily available between packs. The damage potency increase combined with Sacred Soil would either compliment or be unnecessary with this change depending on the numbers.