Oathbow

Weapon (Longbow or Shortbow), Very Rare (Requires Attunement)
When you nock an arrow on this bow, it whispers in Elvish, "Swift defeat to my enemies." When you use this weapon to make a ranged attack, you can utter or sign the following command words: "Swift death to you who have wronged me." The target of your attack becomes your sworn enemy until it dies or until dawn 7 days later. You can have only one such sworn enemy at a time. When your sworn enemy dies, you can choose a new one after the next dawn.
When you make a ranged attack roll with this weapon against your sworn enemy, you have Advantage on the roll. In addition, your target gains no benefit from Half Cover or Three-Quarters Cover, and you suffer no Disadvantage due to long range. If the attack hits, your sworn enemy takes an extra 3d6 Piercing damage.
While your sworn enemy lives, you have Disadvantage on attack rolls with all other weapons.

Make Magical Items with Templates
Magical items can often come with a lot of variants. For example, +1 armor can exist on Light, Medium, or Heavy Armor. For +1-3 armor alone that's 36 items! To keep your Compendia light and speedy we've created Template items which can be used to enchant any item. Now, the Armor, +1, +2, or +3 item and your chosen armor type is all you need! Here's how you can use them:
Open an item like the Armor, +1, +2, or +3, change to the Effects tab, and drag your effect onto your item. This will automatically apply the enchantment, bring over any helpful Activities and Active Effects, and update the item's description with everything you need to know.
To remove an enchantment simply open the enchanted item, change to the Effects tab and right click on the enchantment where you can disable or delete it.