Tome of Bound Flesh

Wondrous Item, very rare (requires attunement by a spellcaster)

This book is painstakingly crafted from humanoid flesh. Its ragged-edged pages are finely made from humanoid skin, inked in blood, and stitched with sinew. The leather cover often displays a humanoid face on its front or is decorated with tattoos, brands, or ritual scars.

A tome of bound flesh contains a wealth of information about humanoid anatomy. A creature who consults the tome has advantage on any checks made within 1 hour to extract information from humanoid creatures by torture. It also provides advantage on Medicine checks on humanoid creatures for the same time. The tome can be consulted 1/day.

The owner of the tome also has one extra spell slot of his or her highest spell level per day. In addition, the owner can invoke the tome's power 1/day to boost the power of a necromancy spell. The spell takes effect as if it were cast with a slot one level higher than the slot actually used. The tome doesn't need to be physically with the owner when these benefits are used.