This has to be the strangest and least detailed quest in WoW, ever...
- Go to the questarea and enter the cave.
- Loot the items on the floor and get an [item=118373] (they are found outside too).
- Click on one of the the crystals in the cave and you get a buff (just 1 crystal is enough).
With this buff you can now kill mobs in the area.
The buff will grow over time and once it reaches 200% you are done.
- After you kill a mob make sure you click its corpse and "consume" him. It looks like you are eating the body (think Undead and their consume racial).
- Take care to avoid the packs of small squids that move about. They hurt alot and give you nothing.
You can also move further into the goblin area:
- Loot the boxes. Click the zapper-things and eventually your buff will reach a level where you evolve into a giant Slithstrider.
- The strider gives you a special toolbar. Run around some more and kill stuff.
- Once you reach 200% you should hear the quest-completed sound.
You can then run out of the questarea and you will get dismounted from the Slithstrider
(this is the fastest way, unless you want to wait around several minutes for the buff to run out).
PS: make sure you check that the quest is completed before you run out of the area.