I just finished The Last Days of Magic by Mark Tompkins, and thought it might be interesting to readers here. The story primarily takes place in late 14th century Ireland as the Sidhe factions and Celts, English invaders under Richard II, the Vatican and a society of exorcists, and a coven of French witches vie for mundane, magical, and religious power. The first few chapters are a bit muddled and clumsy as the main players and plots are introduced, and the present-day prologue and epilogue serve no apparent purpose other than to provide sequel-bait, but the plots-within-plots, betrayals, battles (magical and mundane), and details about life may provide some ArM story and flavor inspiration. At one point, while a magically-aided mundane battle rages, two magicians get locked in what appears to be a certamen-like duel. There are some really nice magic items and religious relics, hedge traditions and druids, bound demons and magical creatures that are I will use in my table-top game.
(I thought about posting this in an earlier thread about literature, but didn't think a four-year-old threadomancy was the best idea. The old thread is here if you're interested: https://forum.atlas-games.com/t/literature-and-such/6628/1.)