Terros’s Captive Core drops from Terros, the 2nd Vault of the Incarnates boss.
Eye of the Vengeful Hurricane drops from Dathea, Ascended, the 5th raid boss.
You must loot both items and turn them in at Ottuk Trader Tattukiaka in Iskaara (The Azure Span).
However, the items are two necklaces and count as gear, and we’re not sure if they will drop as Group Loot, the default option for Dragonflight raids, or Personal Loot, which honestly makes more sense.
There’s an ongoing discussion on Reddit devoted to this topic.
There are no guarantees when you purchase an ottuk from Tattukiaka. At least they’re cute.