I should also mention that the Lore of Shadow might be one of the most common spell lores btw. I haven't done the counting just yet, but the Colleges of Magic, Beastmen Bray Shamans, Dark Elf Sorceresses (Morathi in particular), High Elf Mages, Wood Elf Spellsingers/weavers, Shadow Dancers, Shadow Warriors (Probably), Mist Mages (Most Likely), Mist Walkers (Probably), Drycha (Standard Branchwraith casts from Life, she casts from Shadow), Slann, the Fey Enchantress, the Blue Scribes, Kairos Fateweaver, Lucrezzia Belladonna (Apocryphal, but she chooses Shadow or Death), Vampires, Slaanesh Mages/Daemons are naturally attuned to Ulgu, Chaos Sorcerors in general, Dark Emissaries, Sayl the Faithless, the Lammasu (look them up, you might be surprised), and Fimir Balefiends.