I got stuck in this quest and ran across forums with no help. The quest said complete but it lead me no where and stated I needed to speak to an NPC Martha Kiyen. A GM on another post stated you needed to find her to talk to her again in Calpheon region. She shows up in two spots under Calpheon. I went to both and it did nothing for me. They even posted a picture that was inside one of the locations for the Calpheon shrine priests but no information on how to find it. To the left of Trent there are like three different separate areas that are "Not" connected. If You are stuck at this point pull up the map. Where the symbol for the storage is at in Trent, go left straight from there and you should find one of the 3 Shrine spots. I happened across this one by chance. I thought there was only one spot, till I got the mission and found the 2nd area, then found the 3rd by luck. The inside of this one looks very similar to Serendia Shrine (Kzarka World Boss) with square rooms and winding hall ways. I just happen to turn into a hallway and saw a statue with two a headed snake, stood near it by chance and it said something along the lines of if you enter you will go into a secret area. I entered, got attacked by priests and kzarka was there. It went from cut scene, to cut scene, not sure what happened but by the 3rd cut scene you are taken back out and the NPC is there to turn in the quest. I did my best to just stay alive because during cut scenes you are being attacked and every time i tried to use a health pot it told me "Health potions can't be used in dungeon". Annoying headache if you dont know where to go, and it wont lead you to it. Hope this helps others.

yeah wtf getting attacked by mobs during cutscene
and its like 10fps during cutscene...

Search the Calpheon Shrine until you come across this rectangular room:
Image Link 1

Once you found it, go out the left exit (from my point of view) and you'll be next to some stairs, the NPC (note: the NPC doesn't have a name tag and is therefore hard to see!) and a statue with Snakes:
Image Link 2

Approach the statue and you'll be asked to enter a secret room.

The way this quest works for me is as follows: as soon as I accept it, it shows up as completed and I have to talk to the hidden entrance. The game asks me if I want to continue the quest, I say YES. It then ports me to a Kzarka shrine. The key there is to just wait around until the Kzarka cut scene shows up, then you get ported back outside again and the quest is gone. You have to accept the next quest called "The Qualities of a God" from the NPC next to you. That's it. It's weird, but that's how it works (tested it with two characters).