Rhok'delar, Longbow of the Ancient Keepers (5e Equipment)
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Weapon (longbow), legendary (requires attunement)
This bow is a questreward from the Ancient Petrified Leaf questline that requires you to gather an Enchanted Black Dragon Sinew from an adult black dragon and the heads of four named demons of CR 13-15.
You have a +3 bonus to attack and damage rolls made with this magic longbow, and your weapon attacks score a critical hit on a 19 or 20. When you hit a demon with this weapon, it takes an additional 4d8 radiant damage.