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.

Rod of the Pact Keeper +1, +2 to initiative
Carved when the Old Ones still dwelt amongst their servants, this plaque bears glyphs of such potent cosmic power that those who even glance upon them are driven into a stupor.

Lantern of Tracking (Wondrous Item, common)

This hooded lantern burns for 6 hours on 1 pint of oil, shedding bright light in a 30-foot radius and dim light for an additional 30 feet.

Each lantern of tracking is designed to track down a certain type of creature, which is determined by rolling on the Lantern of Tracking table. Once determined, this creature type can’t be changed. While the lantern is within 300 feet of any creature of that type, its Ylame turns bright green. The lantern doesn’t pinpoint the creature’s exact location, however. This item is found in Icewind Dale: Rime of the Frostmaiden.

Wondrous item, uncommon

While wearing this cap underwater, you can speak its command word as an action to create a bubble of air around your head. It allows you to breathe normally underwater. This bubble stays with you until you speak the command word again, the cap is removed, or you are no longer underwater.

Ring, unncommon This gold ring bears a fluorite stone and is enchanted to sharpen the wearer’s mind. The ring has 3 charges and regains 1d4 − 1 expended charges daily at dawn. When you make an Intelligence check, you can expend 1 charge to grant yourself advantage on the check. This item is found in The Book of Many Things. The surface of the ring is covered is extremely detailed runework that forms a mazelike pattern on its surface and attempting to follow it never seems to work as it should.

Uncommon
Psi Crystal (Wondrous Item, uncommon) (requires attunement by a creature with an Intelligence score of 3 or higher) This crystal grants you telepathy for as long as you remain attuned to it. See the introduction of the Monster Manual for rules on how this telepathy works. The crystal also glows with a purplish inner light while you are attuned to it. The higher your intelligence, the greater the light’s intensity and the greater the range of the telepathy (see the Psi Crystal Properties table). This item is found in Icewind Dale: Rime of the Frostmaiden. Intelligence Score Range of Telepathy Light Intensity 3–7 15 feet Dim light out to a range of 5 feet 8–11 30 feet Bright light in a 5-foot radius and dim light for an additional 5 feet 12–15 60 feet Bright light in a 10-foot radius and dim light for an additional 10 feet 16 or higher 120 feet Bright light in a 15-foot radius and dim light for an additional 15 feet Telepathy Telepathy is a magical ability that allows a monster to communicate mentally with another creature within a specified range. The contacted creature doesn’t need to share a language with the monster to communicate in this way with it, but it must be able to understand at least one language. A creature without telepathy can receive and respond to telepathic messages but can’t initiate or terminate a telepathic conversation. A telepathic monster doesn’t need to see a contacted creature and can end the telepathic contact at any time. The contact is broken as soon as the two creatures are no longer within range of each other or if the telepathic monster contacts a different creature within range. A telepathic monster can initiate or terminate a telepathic conversation without using an action, but while the monster is incapacitated, it can’t initiate telepathic contact, and any current contact is terminated. A creature within the area of an antimagic field or in any other location where magic doesn’t function can’t send or receive telepathic messages.