Arianwyn Cadarn is the leader of the rebel elves' settlement of Lletya. He is first encountered by players in Ardougne at the end of the quest Regicide, after which he can be interacted with in the building at the very east end of Lletya. Players must have started Mourning's End Part I to enter Lletya and encounter Arianwyn. Arianwyn is heavily featured in the quests Mourning's End Part I and Part II.
In Song of the Elves, Arianwyn rescues the player and Elena after being kidnapped by Lord Iorwerth. After learning Seren's dark secret, he becomes dismayed and switches side to the Iorwerth clan. The player must then defeat him during the battle of Lletya. After the Fragment of Seren is defeated, he realizes the error of his mistakes and temporarily stays behind to rebuild Lletya and see Prifddinas for the first time before departing in self-exile.
After completion of Song of the Elves quest, Arianwyn (referred to in the interface as Elven Traitor) can be fought in the Nightmare Zone minigame.
Arianwyn is a boss in Song of the Elves. Arianwyn cycles through three ranged attacks:
- A green arrow is a regular attack which can be negated with protect from missiles.
- The orange arrow is a high damage explosive attack that hits through prayer, up to 50+ damage . It is a slow moving attack, so to avoid it move one block away.
- The purple arrow disables active prayers, but does not cause damage.
- 'Arianwyn Cadarn' appropriately means 'strong leader' in Welsh.
- If players attempt to talk to him after completing the quests they'll receive the "Nothing interesting happens." message.