Magic Items

It uses the stat block of a giant poisonous snake.
The serpent is a construct that understands and obeys whoever was holding the staff when it transformed.
It has immunity to poison damage and the poisoned condition. It doesn’t require air, food, drink, or sleep.
When it drops to 0 hit points, roll a d6. On a roll of 1, the snake turns to dust and is destroyed. On any other roll, it changes back into a staff and breaks into 1d4 + 1 pieces that must be magically mended before the staff can be used again.

Shield, very rare (requires attunement)

While holding this Shield, you have Advantage on saving throws against spells and other magical effects, and spell attack rolls have Disadvantage against you.

Wondrous Item, Very Rare (Requires Attunement by a Wizard) This old book, titled “Book of Trios,” is remarkably well-preserved. Its brown and gold cover is coated with a fine layer of pixie dust, which gets on everything it touches. When a spell is cast from the book, the pixie dust swirls into a glittering aura of arcane energy around the caster. While you are holding this leather-bound book, you can use it as a spellcasting focus for your wizard spells, and you gain a bonus to spell attack rolls and to the saving throw DCs of your wizard spells. The bonus is determined by the book's rarity (+3). You can use this book as a spellbook. In addition, when you use your Arcane Recovery feature, you can increase the number of spell slot levels you regain by 1.