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Armor of the Viper.
The armor of the viper was an enchanted suit of leather armor found in Faerûn during the 14th century DR. While it provided significant protection against physical attacks, it left the wearer more vulnerable to poison and paralyzation.
The armor got its name not from a monstrous snake or serpentfolk but rather from the nickname of the drow assassin, Raroh. He was renowned for the potent poisons he used in his murders. When he learned of his armor's susceptibility he presented it as a gift to Avlorm, a skilled but novice assassin, who was quickly rising in rank within his guild. When the novice's prowess eventually grew to rival his own, Raroh easily eliminated the threat to his power.