Step 1: Complete Bogling Star Signs shiny collection. No progress can be made without this collection unless you nabbed a copy of the completed book from Mort on live during the beta testing (you'll know if you did). While you're doing this you can also gather some gems that you'll be using later on, including a ruby, brilliant diamond, radiant emerald, sapphire and moonstone. These are just mining items and should be cheap to get. Get one of each.
Step 2: In order to hand the pages in for the book you need to find M'doidoi dolls. You'll need nine and you can find them in Argent Domain. Krondor has made a video for the achievement which can be found here: http://youtu.be/0DGW8c4NyWk
Once you find all 9 M'doidoi return the completed artifact set and the dolls to Omi, the bogling in the water near the Manufactory in TB. She will give you the book you need to go further, and it also has clues in it if you want to try the puzzle without a complete spoiler.
Step 3: To get inside the instance add the book to your collection and go to Eastern Holdings, around 8800.8750 there is a pond. Dive down and you will find a portal. Interact with the plaque at the door to get inside the instance.
The puzzle here is underwater so you'll want to bring either your water breathing trinket, potion, or simply use the air vents inside the instance that give you a breathing buff for 5 minutes.
During this step you will also need to visit Mort Grocer in Stillmoor and buy his Fat Worm Offering and also visit two other vendors that sell the fish, beetle, crab and apple offerings. Robyn Hutchinson in Freemarch is in the village with the disguised deep ones. She stands under a market stall and sells the crab and apple offerings. Vera Coyle is also in Freemarch on the east shore at Denegar's Stand. She sells the beetle and fish. Collect at least one of all of these offering items. Using an offering can be wasted if you use it incorrectly, so if you want to be sure just buy more than one of each.
Step 4: Upon entry you will see some pillars inside. These are the "traps" for your boglings.
The order is this:
Activate a star sign.
Locate the bogling and use your reactive ability with the right offering.
Lead the bogling back to the lamps and interact the right one with the correct gem (the correct gem should automatically work with it.)
When all five boglings are trapped you will get a key. The key opens a chest in the right-hand back room of the instance.
The combinations are the following, as deduced from the book "bogling star signs":
Zeek, sign of sword, lured by beetle into tin lamp with ruby
Pfeef, sign of club, lured by apple into silver lamp, moonstone
Mok, sign of axe (haft starts at door, axe blade criss crosses in middle) lured by fat worm into brass with emerald
Krell, sign of spear, (haft starts at right hand side near door, goes diagonal to left hand upper point), likes fish, locked into copper lamp with sapphire
Grimoo, sign of shield has a squiggly bottom, found on right hand side middle from entry, likes crab, trapped into gold lamp with diamond
The signs are shown in the image below, and you make them by clicking on the red gems on the ceiling above the lamps. Activate them one at a time, as if you have any other stars activated it will not work.
Reward: Achievement, purple item, dimension based on the BB puzzle instance.