Wondrous item, legendary (requires attunement by a spellcaster)

Dark Spells and Rituals:- Grants access to powerful spells and rituals that are typically forbidden or dangerous, such as casting curses

Enhanced Magical Power:- Increases the spellcasting ability of its wielder, possibly providing additional spell slots, higher damage, or extended range and duration of spells.

DownSide) Corrupting Influence:- The grimoire has a corrupting effect on its wielder, gradually influencing their alignment or sanity, leading them towards evil or chaotic actions.

Abyssal Resilience: Grants resistance or immunity to certain types of damage, such as fire or necrotic damage, typically associated with the abyssal planes

Shadow Manipulation:

   - Allows the wielder to manipulate shadows, creating areas of darkness, summoning shadow creatures, or teleporting through shadows.

Mental Domination:

    - Provides spells or abilities to dominate or control the minds of others, bending them to the wielder's will.

Eternal Binding:

    - Grants the wielder the ability to trap souls within the grimoire, using them as a source of power or as a bargaining chip with demonic entities

Notes: To attune to the Abyssal Grimoire, a spellcaster must spend 1 hour holding the book and reading its forbidden pages by candlelight. During this time, they must succeed on a DC 18 Wisdom saving throw or be afflicted by a form of long-term madness (as per the Madness rules in the Dungeon Master's Guide). The madness lasts until the attunement ends.