Feywild Eusdria as Grimm Fairy tale Black Forest
by Marc SaindonWhile the Feywild is a 4e concept not found in Mystara, there is 'the Good Kingdom' that can wedge it in as a retcon. The Black Forest of the Grimm Fairy Tales (with their own Mystara variants) would make an interesting realm, Halloween season and otherwise. Alfheim Forest seems unsuitable for it (it already has the aforementioned Good Kingdom); germanic Hattias doesn't have the right climate; the Northern Reaches are too far north and too viking; Norwold is too canadian; Glantri lacks impressive forests in its germanic-speaking regions; Kogolor would be too weird. And so Mystara's Austria, Eusdria, makes for the most likely candidate.
The denizens of the Dark Forest are of course unseelie for the most part, with Crones and Witches and Dark Queens keeping the noble knights of Eusdria busy with curses to break, plots to foil and monsters to vanquish. Some tales might be updated, so a lost dwarven party might stumble on a tavern that advertizes 'Free Beer' as a trap reminiscent of Hansel and Gretel (with the wenches being hungry Crones).
Eusdria map: https://mystara.thorfmaps.com/dragon178-eusdria-8/
(pic from: https://buffaloescaperooms.com/the-grimm-forest-all-new-escape-room-opens-july-26th/)