Book of Vile Darkness

Antimagic Susceptibility. The Book of Vile Darkness is incapacitated while in the area of an antimagic field. If the grimoire is targeted by dispel magic, it must make a Constitution saving throw against the spellcaster's DC or fall unconscious for one minute.

Magic Resistance. The Book of Vile Darkness has advantage on saving throws against spells and other magical effects.

False Appearance. While the Book of Vile Darkness remains motionless, it is indistinguishable from a normal book.

Innate Spellcasting. The Book of Vile Darkness is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 17, +9 to hit with spell attacks). The Book of Vile Darkness can cast spells contained within it that do not require material components and are not rituals. If an ally commands the Book of Vile Darkness to cast a spell, it will cast the spell that it believes is most appropriate to accomplish the task.

Enmity of Life. Nature can’t abide the book’s presence. Ordinary plants wither in its presence, animals are unwilling to approach it.

Book Bite. Melee Weapon Attack: +9 to hit, reach 5 ft. Hit: 6 (2d8 + 5) bludgeoning damage.

Dark Speech. The Book of Vile Darkness can use an action to recite words from its pages in a foul language known as Dark Speech. Each time it does so, it takes 1d12 psychic damage, and each non-evil creature within 15 feet of it takes 3d6 psychic damage.

Reactive Spellcasting. If the Book of Vile Darkness is damaged, it rolls 1d10 and casts one of the following spells defensively, targetting the source of damage if possible. It can use this reaction up to 3 times per day. If it is not possible to target the source of the damage, the Book of Vile Darkness will instead target the nearest creature it can see. If there are no creatures within the spell's range, the Book of Vile Darkness instead takes the Hide action. 

1. chill touch
2. hellish rebuke
3. ray of enfeeblement
4. hunger of hadar
5. summon greater demon
6. insect plague
7. circle of death
8. reverse gravity
9. abi-dalzims horrid wilting
10. weird

Spells with an area of effect target all creatures within that area. Creatures summoned by the Book of Vile Darkness are friendly toward it and hostile toward all other creatures they can see.

Instrument of Evil. The Book of Vile Darkness is compelled by its nature to perform acts of evil. It must perform at least one evil act every 10 days. Failure to commit an act of evil in this timeframe, or willfully performing a good act, causes the Book of Vile Darkness to implode, destroying the book and doing 8d8 necrotic damage to all object or creatures in a 30ft emanation from the book.