Curse of Farcast

Talking to Reldo
After finishing the Dragon slayer quest, a new option will appear if you talk to Reldo the Librarian: "I'm bored. Do you have a cool book I can read" and Reldo will reply "Sure, there's a book I found something the other night...Something to do with an extinct society called the Farcasts...Its right their in the west shelf, bright red book".

Search the west book shelf until you find "Ancient stories of old". Read page 3-4 and it will tell your character the story and information of Farcast.

The curse
Teleport to Lumbridge and walk to Wizard's tower. Go down to the basement and talk to head wizard Sedridor. Talk to him about the Farcast (Sedridor is one of the few people to know who the Farcasts are) and he will tell interrupt saying you are one of the descendants of those who had hunted the Farcasts ages ago meaning you are cursed! Talk to him about how to uplift the curse and Sedridor will say "Over my countless adventures I have found evidence that a Farcast mage is still at large but is very weakened and is disguised as an elderly man. You: How do I find him? Sed: I don't know, the only evidence I got is a mysterious talisman no one has ever seen before except for Lord Saradomin of course. You:Can I see the Talisman? Sed:Only if you can proove to me that you are a worthy hero! (If you have Rune platebody in your inventory show him, if you are already wearing it you won't have to) Sed: A Rune platebody! One of the most strongest armors Gielinor has ever forged! THis is more than enough to show me your a hero! (If you don't have Rune platebody or is somewhere else such as the bank or someone has borrowed it) Sed:Sorry but only the most braviest can see this artifact. Please bring me a token of worthness of some sought. (Once you have shown Sedridor he will show you the Talisman) You: Woah! Its the most strangiest and oldest thing I have ever put my eyes on! Can I please borrow this for my further investigation? Sed: Alright but only for a while (You will borrow the Talisman from Sedridor for 24 hours.If you haven't finished the quest by this time you will have to borrow the Talisman again.