The Goblin Betrayer

[The Goblin Betrayer] is a quest mob found in the hub zone (currently TutorialB (tutb))

To complete this quest you will need to kill 4 goblins across a number of Kunark Zones.

[The Goblin Mystic] is located in Firiona Vie on the way to Dreadlands. Respawn Time is approximately 20 minutes.
[The Goblin Elementalist] is locaed in Frontier Mountains. Respawn Time is approximately 5 Minutes
[The Goblin Diviner] is located in Warsilks Wood. Respawn time is approximately 20 minutes.
[The Goblin King] is located in Nurga. This fight is more difficult than the rest (Hits for up to 5k, others hit for 1 damage and are just DPS tests). Respawn Time is approximately 10 minutes.

They can drop either a Silver (90%) or Gold Coin (10%). You need all 4 to get the reward.

Silver - [Ring of the Goblin Lords]
Gold - [Talisman of the Goblin Royals]