The fine folks at Chaosium have recently released The Grand Grimoire of Cthulhu Mythos Magic which collects just about every spell from practically every Call of Cthulhu adventure published by the company (over the last thirty plus years) and converts them to the 7th edition rules. We’re talking about two hundred pages packed not only with eldrich lore but also with plenty of advice regarding spell casting for Keepers. The print book arrives later this year but you can grab the PDF right now for $19.95.
From Chaosium:
Over 550 spells of dire consequences, secrets, and unfathomable power!
Here are gathered spells drawn from over thirty years of Call of Cthulhu supplements and scenarios. Each spell has been revised for the Call of Cthulhu 7th edition game, including optional Deeper Magic for the most powerful of Mythos sorcerers and monsters, with which to beguile and confound investigators.
Packed full of advice and guidance on diverse matters including spell names, elements of spell casting, magical components, and astronomical considerations. Plus flawed spells, ley lines, folk magic, and the magic of the Dreamlands. Use this grimoire as a resource, a play aid, and as inspiration when designing scenarios. The Grand Grimoire of Cthulhu Mythos Magic is an essential supplement for Keepers of Arcane Lore.