Magic Items

Wondrous item, common

This horn has 4 charges and regains 1d4 expended charges daily at dawn. As a Magic action, you can blow the horn while expending 1 charge. One creature of your choice hears the horn's blare, provided that creature is within 600 feet of the horn. No other creature hears the horn.

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.

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.

Armor (medium or heavy, but not hide), uncommon

Mithral is a light, flexible metal. A mithral chain shirt or breastplate can be worn under normal clothes. If the armor normally imposes disadvantage on Dexterity (Stealth) checks or has a Strength requirement, the mithral version of the armor doesn’t.

Wondrous item, common

This orb can be used as an Arcane Focus.
While holding this orb, you can take a Magic action to determine which way is magnetic north. Nothing happens if the orb is used in a location that has no magnetic north.
This seemingly plain glass orb once held a mote of Halaster Blackcloak, known as Professor Halaster. Maybe it will again in the future…

This common wondrous item is a hollow, 5-inch-diameter orb that weighs 5 pounds. Its outer shell is composed of notched bronze rings, which can be turned so that the notches line up. Aligning the notches requires an action, and doing so causes the orb to gong loudly until the notches are no longer aligned. The sounds are spaced 6 seconds apart and can be heard out to a range of 600 feet.

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.

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.

The rapier is flavored as "Rapier of the Dark Huntsman". If you're curious about the flavor text:

"Weapon, rare (requires attunement) This matte-black rapier does not reflect light. It radiates a faint fiendish aura, and turns chill to the touch when within 30 feet of a good-aligned cleric or paladin. Once attuned, the wielder often feels hungry, even if they have just eaten. However, when the life stealing power is used, the wielder experiences an invigorating euphoria and feels satiated. The blade glows dully when it has fed. When you attack a creature with this magic weapon and roll a 20 on the attack roll, that target takes an extra 10 necrotic damage if it isn't a construct or an undead. You also gain 10 temporary hit points. Proficiency with a rapier allows you to add your proficiency bonus to the attack roll for any attack you make with it.

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.

Wondrous item, uncommon

Sending Stones come in pairs, with each stone carved to match the other so the pairing is easily recognized. While you touch one stone, you can cast Sending from it. The target is the bearer of the other stone. If no creature bears the other stone, you know that fact as soon as you use the stone, and you don't cast the spell. Once Sending is cast using either stone, the stones can't be used again until the next dawn. If one of the stones in a pair is destroyed, the other one becomes nonmagical.

Unlike most sending stones, these are natural, unworked stone. These were the very first magic items added to Mornauguth’s horde; that she gave them to you freely either means you should be terrified or grateful.