If you are trying to farm Terokk for the item Time-Lost Figurine for your Toy Box before 6.0/WoD this is a mini-guide explaining how to do so.
Here are the steps you must take to be able to summon Terokk:
1.) Get the quest Adversarial Blood from Hazzik at the Skettis quest hub.
2.) Go south and farm Shadow Dust from the Arakkoa in the area (I suggest farming atleast 30 dust). Every 6 dust you get can be turned in to receive an Elixir of Shadows. You need to use an Elixir of Shadows to be able to see the Arrakoa that drop the Time-Lost Scrolls. Time-Lost Scrolls are what you need to summon the 4 'mini-bosses' that you must kill to complete this quest. You need 10 scrolls to summon each mini-boss.
3.) Once you have 30 or so Shadow Dust go and turn them in to Severin at the Skettis quest hub to the north of where all the Arakkoa are. If you farmed 30 you will get 5 Elixir of Shadows. Each Elixir lasts 20 minutes.
WARNING: Make sure you have this quest (Adversarial Blood) before continuing step 4.
*Tip for step 4:* From my experience, the majority of the shadowy Arakkoa are in the tree-house area's and near the ruins on the ground.
4.) Now that you have a few Elixir of Shadows you can go back to where the Arakkoa are and pop your Elixir. You will now be able to see shadowy Arakkoa as well as all the regular Arakkoa. The shadowy Arakkoa are the ones that drop the Time-Lost Scrolls.
5.) Once you have farmed your 40 scrolls you are ready to summon the 4 mini bosses. When farming your Shadow Dust and Time-Lost Scrolls you likely saw some purple/pink ruins on the ground. In the middle of the ruins there will be a pile of skulls. If you right click on the skulls you will be able to choose between 4 different mini-bosses. Summon the top one and kill him. Then find another skull pile, and kill the 2nd one on the list and so on. After you kill all 4 of them you can turn this quest in to Hazzik. You will be awarded with a Time-Lost Offering.
You might be asking why this quest is necessary for farming Time-Lost Figurine from Terokk. Each of these 'mini-bosses' drop an item that you will need to summon Terokk. After you complete this quest "Adversarial Blood" you will receive a Time-Lost Offering. This is the item you need to summon Terokk. Now you can head to the little island in the center of the lake near in Skettis. There will be a big purple/pink ruin with a skull pile in the middle. Click on it, and you can use your Time-Lost Offering to summon Terokk. According to Wowhead Terokk has a 9% chance to drop the Time-Lost Figurine. In the case that he doesn't drop it on your first kill you will need more Time-Lost Offerings. After you complete Adversarial Blood the quest giver will have a repeatable quest that asks you to farm the 4 items which dropped by the mini-bosses (Gezzarak's Claw, Akkarai's Talons, Karrog's Spine, and Vakkiz's Scale). Completing this repeatable quest will reward you with another Time-Lost Offering.
The skull pile that is used to summon Terokk seems to respawn approximately every 15 minutes or so.
I am new to writing short 'guide' comments on Wowhead so I apologize if it is more 'wordy' than necessary. And I apologize for any typo's there might be. I hope this guide saves you some time. Please share your opinion on this mini-guide by up or down voting it and feel free to leave a comment on how I might be able to improve in the future.
Thank you.