From publisher blurb: Unnameable Secrets of the Great Old Ones! Some warlocks, wizards, and clerics deal with creatures far worse than demons and devils — malevolent alien beings from beyond space and time. These entities’ minds are immeasurably superior to our own. Their sinister, loathsome agendas challenge not only our sanity, but our very existence. And yet, and yet…the revelations they offer… The 20 scrawled and creeping pages of Deep Magic: Mythos Magic bring the magic of classic cosmic horror tales into your 5e campaign, featuring: Grimoires of the Cthulhu Mythos, including the Necronomicon Rules for tracking the mental and physical corruption that result from learning Mythos spells 20 new spells, including black goat’s blessing, emanation of Yoth, sleep of the deep, yellow sign, and more As a Mythos caster you have the power to summon sanity-shattering servitors, warp reality, and even make the stars right again through force of will. The cost is too terrible to contemplate, but you will follow this path wherever it takes you, and face whatever doom awaits you at the end.