You must acquire the Medallions of Kunzar and Nathsar, and give them to Emperor Ganak. He will reward you with Trakanon Idol which is the key to Old Seblis.

The Medallion of Kunzar Is found on the Froglok Forager in Trakanon's Teeth. When kill another one will immediatley respawn. The Forager in itself in not hard to kill but there are many mobs in this zone that wander and adds are very easy. Several mobs here see invis as well.

Medallion of the Nathsar is found on the Froglok hunter in Trakanon's Teeth. The hunter tends to wander closer to the emeral jungle zone line than the forager. Most people try to pull the hunter to the zonline to kill him so any adds can be handled easier. Another tactic for the soloer is to pull the hunter to zoneline and root him and zone out to clear aggro from the adds. With a little luck the hunters root will not have broken and you can zone back in and kill him alone. This tactic can be used for the forager as well but he usually wanders deeper in the zone so it's more difficult.

The medallions are no-drop and lore. So everyone in your party will have to grab one of each.The idol itself does not have to be on your person to work. you can have it in the bank and still get into seblis.

Once you have both parts of the medallions, you now need to turn them in to Emperor Ganak. You will need someone that can cast invisibility to undead with you to do this part. It can be done without it but it's a little risky. There are alot of undead right outside the enterance to his cave. If you don't want to chance it go buy a potion of unlife awareness and use it to Invis yourself.

If you zone in from Emerald Jungle and follow the wall to right, go all the way south till you find his temple at approximate loc -2700, +2800. Now follow down the ramp and you should see him at the bottom. He's a ghost iskar, don't worry he will not aggro on anyone unless attacked.

Here's a MAP to show you where he is he's #5

Turn in both pieces to the Emperor and you will receive the Trakanon Idol. This is your key into Old Sebilis.