Source: DMG-179

Weapon (javelin), uncommon

This javelin is a magic weapon. When you hurl it and speak its command word, it transforms into a bolt of lightning, forming a line 5 feet wide that extends out from you to a target within 120 feet. Each creature in the line excluding you and the target must make a DC 13 Dexterity saving throw, taking 4d6 lightning damage on a failed save, and half as much damage on a successful one. The lightning bolt turns back into a javelin when it reaches the target. Make a ranged weapon attack against the target. On a hit, the target takes damage from the javelin plus 4d6 lightning damage.

The javelin's property can't be used again until the next dawn. In the meantime, the javelin can still be used as a magic weapon.

Source: DMG-159

Wondrous item, uncommon

While wearing this cloak with its hood up, you can breathe underwater, and you have a swimming speed of 60 feet. Pulling the hood up or down requires an action.

Source: DMG-194

Wondrous item, legendary (requires attunement by a sorcerer, warlock, or wizard)

This elegant garment is made from exquisite cloth of white, gray, or black and adorned with silvery runes. The robe's color corresponds to the alignment for which the item was created. A white robe was made for good. gray for neutral, and black for evil. You can't attune to a robe of the archmagi that doesn't correspond to your alignment.

You gain these benefits while wearing the robe:

• If you aren't wearing armor, your base Armor Class is 15 + your Dexterity modifier.
• You have advantage on saving throws against spell and other magical effects.
• Your spell save DC and spell attack bonus each increase by 2.

Source: DMG-212

Wand, uncommon (+1), rare (+2), or very rare (+3) (requires attunement by a spellcaster)

While holding this wand, you gain a bonus to spell attack rolls determined by the wand's rarity. In addition, you ignore half cover when making a spell attack.