Wondrous item, uncommon (+1), rare (+2), very rare (+3) (requires attunement by a wizard)
As per this magic item while you’re holding this particular leather-bound book, you are easily able to use it like a spellcasting focus for your wizard spells, and of course you shall gain the bonus to spell attack rolls and eve to a saving throw DCs of your wizard spells. Usually, the bonus action has been determined by a book’s rarity.
You can easily use this book as a spellbook. In an addition, when you use your Arcane Recovery feature, then you can easily enhance the number of spell slot levels that you regain by 1.