R'lyeh (5e Equipment)
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Weapon (greatsword), legendary (requires attunement of a creature of chaotic evil alignment)
R'lyeh is a multidimensional blade from the lost city of the same name. It was recovered by "The Messenger" while the city was above the ocean after Lord Cthulu was failed to be summoned correctly. You gain +1 to attack and damage rolls made with this weapon. It also has the following additional properties.
Silent Rage. While attuned to this weapon it bestows power resembling that of a Barbarian's Rage. You gain +4 to damage rolls and can add three extra damage dice determining the extra damage for a critical hit with a melee attack. Before making a melee attack with R'lyeh you can choose to gain advantage on all attack rolls for the remainder of your turn. If you do, all melee attacks made against you gain advantage until the beginning of your next turn. Creatures you attack that are Frightened take an additional 6d6 slashing damage.
Vocal Terror. R'lyeh can terrorize nearly any being. It screams loudly into the minds you desire to conquer. As an action, creatures you choose within 60 feet of you must succeed on a DC 18 Wisdom saving throw or become Frightened of you for one minute.
R'lyeh desires only two things; the destruction of living things and to please its true masters. Its owner is a means to both those ends and for that it is grateful. Its lust for murder must be catered to tediously. A conflict occurs if it goes 24 hours without reducing a creature to 0 hit points.