Zalon is a longbow of the oath of death, when a creature takes the oath of death, you gain the advantage on all your attacks against the creature, 19 natural is considered critical and you deal +1d8 damage to the creature every hit. You can only swear one other creature at the next dawn, regardless of whether the creature has died or not.
As long as a creature sworn to death is alive, you have a disadvantage to all attacks against other creatures.
The pact with this bow is broken if you use another ranged weapon. Once the pact is lost you cannot restore it.
You have a +1 bonus to attack and damage rolls made with this magic weapon.

Proficiency with a Longbow allows you to add your proficiency bonus to the attack roll for any attack you make with it.

Notes: Bonus: Magic, Ranged Weapon Attack: Piercing, Damage, Combat, Ammunition, Heavy, Range, Two-Handed, Slow