We are just finishing the War against davnalleus.
The basic profiles for the characters are:
PRALIX: Spirit Master. Summoning, Binding. Puissant Bargain, Chtonic Magic. Driven. High Presence. High leadership, charm and bargain. Leadworker, IIRC.
IGNES FESTI: We used the Hyperorean Hymnist template. Pserimpseu and Azai hymns. Magical Blood (Focus in flames, Pride flaw) Minor focus in Flames. We used a variation that allowed him to cast spells using +1D6 (we use D6, not D10) to his spells instead of a fixed casting total, and so he could also use Penetration with them. He was also allowed to cast spontaneous spells using vis (1 pawn per intended magnitude).
BRUDE DEATHLESS: Standard gruagachan. He was more advanced than the other 2, having an external soul. (Hedge) prestige. His team of gruagacvh and trained grogs to fight in giant form had some epic battles against similarly-styled groups on the other side (but the other sincluded real giants as well!).
BLACK EYE: Folk Witch. She is an invented character that favours her shape as a crow. She was one of the most powerful characters in the saga, in the end, using a multiplicity of abilities to achieve pretty nice results. She had Hermetic Herbalism, Hex and Chtonic Magic instead of Healing and Cursing.
CORMAC: Storm warlock (elementalist). Uses the whistle up the wind mechanics and the Elementalist abilities that allow you to enslave a spirit (I do not control these rules, so no details here). A last addition after the death of Ignes Festi.
MOOD BOOKS: The Northmen saga by Bernard Cromwell has helped wonders to set up the mood for us. King Hereafter (McBeth's story) is also good even if it is set in a later (XI century) period.
DEVELOPMENT OF THE MINI SAGA
We have disregarded the rest of the OoH since they do not play a large part in this mini saga. Allies include folk witches, gruagachan (very few in number; most of them were with Davnalleus), damhaidh druidsan, and Nightwalkers. The opposite party had more or less the same components, but with more gruagachan and Damhaidh Druidsan as well as the Sluagh (Infernal Nightwalkers) and more dark fae. Weather witches (whistle up the wind) and Animal masters are also present on both camps.
The Diedne have been portrayed as Chtonic Infernalists mechanically (adding Ceremony on top of that), but using powers that are not infernal. They have not played a magical part in the war, preferring to centre in their own conflicts with the Vikings and the vitkir, since those are happening at the same time. The contact we had with the Diednes were cautious and tense, but ended up badly and this allowed the PC to say things like "In the time of need you are abandoning us! You will end up paying for this betrayal!". "Player Augury" powers FTW.
There have been contacts with Vitkir, but nothing definitive came out of it except a negotiation that ended with the summoning of the Manx sea spirit to allow free passage for the viking ships of Olaf Sigurdson (fictional character) for 10 years in exchange for an item that cast a powerful light that we used in the battle of the False Sun. Really useful item. The vitkir have so far refused to join the war effort, though, even if they are making overtures now that they have seen us emerge as the victor. We had a side scene about Saxons enslaving a pair of vitkir to learn their secrets, just for fun.
Davnalleus has already fled, and we are thinking about running the formation of the House or not. It is likely that we will not since we already had a highly political end-game for our past saga. After this we will start on our Order of the Hedgies saga in Triamore.
Hope that helps, even if it is a different kind of saga than what you are looking for. We used this as a test bed for our hedgie saga (power levels and the like), so we handwaved a lot of things and does not seem to be exactly what you want (not hermetic at all) but it worked well for us.