Warning, this page contains spoilers. If you find yourself stuck or looking for a place to start then you're in the right place.

Previous - Quest 2: Realm of Eternal Darkness (part 1)
Once you have defeated the monsters, head to the crypt.

You can either get close enough to click on the door or just run into it.

Once at the hidden crypt pick up the Realm of Eternal Darkness Krystal and head back to your Adobe.
At your adobe put the krystal in your Ka-Ra by clicking on it.

Now the path to the Cathedral and Krystal Kaverns is open to you.