Quaryl's Codex (Tome of the Stilled Tongue)

Legendary

Wondrous Item, legendary (requires attunement by a wizard) This thick tome contains pages of thin, hammered copper and has thing covers of slate. It is held shut by a severed elven tongue. Occasionally, the attuned user of this spellbook finds messages that have been scrawled by someone claiming to be Netherese; this ghostly writer refers to itself simply as “the warlock” and frequently opines on the power of the one true god of magic: Mystryl. If you can attune to this item, you can use it as a spellbook and an arcane focus. In addition, while holding the tome, you can use a bonus action to cast a spell you have written in this tome, without expending a spell slot or using any verbal or somatic components. Once used, this property of the tome can't be used again until the next dawn. While attuned to the book, you can remove the tongue from the book's cover. If you do so, all spells written in the book are permanently erased. Vecna watches anyone using this tome. He can also write cryptic messages in the book. These messages appear at midnight and fade away after they are read.

Holy Avenger (Longsword)

Legendary

Weapon (any simple or martial), legendary (requires attunement by a Paladin) You gain a +3 bonus to attack rolls and damage rolls made with this magic weapon. When you hit a Fiend or an Undead with it, that creature takes an extra 2d10 Radiant damage. While you hold the drawn weapon, it creates a 10-foot Emanation originating from you. You and all creatures Friendly to you in the Emanation have Advantage on saving throws against spells and other magical effects. If you have 17 or more levels in the Paladin class, the size of the Emanation increases to 30 feet.