Viyeldi is a spirit of a sorcerer who guards the Viyeldi caves. He was the first person to die while searching for the source of the pure spring water in the Kharazi jungle, and thus was cursed to act as its guardian. He controls the spirits of the three heroes who later died while searching for the source - San Tojalon, Irvig Senay and Ranalph Devere, and ensures that they protect the caves.
He is encountered during the Legends' Quest, when Nezikchened disguised as Echned Zekin asks you to kill him. When you first enter his room, Viyeldi pretends to be a hat on the ground until picked up. Upon beginning a conversation with him, he informs you how to get to the source of the holy water spring, by killing the warriors for the fragments of the Heart crystal to progress.
Later in the quest, Echned Zekin requests that players kill Viyeldi using a dark dagger, claiming that he is an evil wizard who is tormenting him. If you choose to kill Viyeldi, while it is quicker, it results in a more difficult final fight, as you will have to defeat the three warriors San Tojalon, Irvig Senay, and Ranalph Devere alongside Nezikchened in the fight, as they are no longer under his control. You can avoid this if you listen to Viyeldi and give the dagger to Ungadulu instead. Ungadulu will also give you a Holy force card to use against Nezikchened and weaken him in the next two fights. If you do kill Viyeldi with the dagger, you may still give the charged dagger to Ungadulu to receive the Holy Force card. Just remember that this route results in the three warriors appearing in the final battle.
It was possible, up to approximately 2005, to telegrab Viyeldi's hat. Dropping and picking it up caused the player to teleport back to the Viyeldi's cave (starting an animation sequence), even if the player was in the wilderness or the Duel Arena. Jagex fixed this problem approximately 2 weeks after it was discovered, resulting in the first un-telegrabable item.