Blood Magic, Witchery, DyeTrees, Roguelike Dungeons, GeoStrata, Bibliocraft (magic mods without proper shelving?!) and possibly TiCo, which at its core has always felt very medieval to me.
I'd prefer to have Forestry and Binnie's mods too, for a magic pack, but that's starting to get into machines and automation and cross mod support, although you could restrict it to clockwork engines only, which I feel would give a fairly cool feel to your world.
Er, Magical Crops too, for me anyway.
Sent from my HTC One using Tapatalk