Hello Candangoek!
Actually this is one of the easiest bosses to check, because you can check it with a Level 8 ED using an Stealth Ring and 3 parcels.
There is 2 ways to bring your maker to this place, 1 cleaning the way with your main char or 2 by asking for a friend to clean the way, this is only needed kill the dragons and the orcs that are around the entrance that can see you through the invisibility.
So after you bring your maker with enough stealth ring and 3 parcel you only have to choice with side you want to stay, left or south.
Use parcels to go up and down and you will easy have a way to check if Fernfang is arrive!
Hope this help you!