Enchanted key notes are an item obtained during the beginning of the Meeting History quest. According to Jorral, the owner of the Outpost north of West Ardougne, he found the documents within the Outpost's files.
The notes briefly describe a second purpose of the Enchanted key, telling of their use to time travel. When players use the key to teleport, the notes dissolve.
Scraps of info on the enchanted key:
Eureka! I’ve done it! The key now returns to its origins. It really does get hotter and colder depending on your proximity – so strange. Its other special function only seems to work north of the river, after smelting it. I’ve bound it with the words “Predem abducto’ – good words, I think, they have a certain ring to them.
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