The amulet of othanian is an item used in the later stages of the Underground Pass. It is obtained by killing the level 91 demon Othainian. Once Othainian and his comrades Holthion and Doomion have been killed, the player can use their amulets to open a chest that contains Iban's shadow.
After the quest, the amulets cannot be obtained and have no other use.
For an exhaustive list of all known sources for this item, see here
- The name of the amulet is spelled "othanian", despite the demon being named "Othainian". The amulet is also misspelled in RuneScape 3, but is correct in RuneScape Classic.