Javelin of Warning

As long as this weapon is within your reach and you are attuned to it, you and allies within 30 feet of you gain the following benefits.

Alarm: The weapon magically awakens each subject who is sleeping naturally when combat begins. This benefit doesn't wake a subject from magically induced sleep.

Supernatural Readiness: Each subject has Advantage on its Initiative rolls.

Slow (Mastery): If you hit a creature with this weapon and deal damage to it, you can reduce its Speed by 10 feet until the start of your next turn. If the creature is hit more than once by weapons that have this property, the Speed reduction doesn't exceed 10 feet.

Thrown: If a weapon has the Thrown property, you can throw the weapon to make a ranged attack, and you can draw that weapon as part of the attack. If the weapon is a Melee weapon, use the same ability modifier for the attack and damage rolls that you use for a melee attack with that weapon.

Proficiency: simple, javelin Source: Dungeon Master's Guide (2024) p. 324