Tavon Vastsea  

If you are without cleric 1.0 he will give you a side quest:

Tavon Vastsea says "Greetings Cashiuus. I am afraid that I need someone that I can [trust] with this task, these are dark times, and it is hard to tell friend from foe.

you say "you can trust me"

Tavon Vastsea says "Hmmm, well I think I have a task I can entrust you with. Speak to my brother, tell him that I sent you to him. Earn his trust, and you shall have mine."

Head to TD, to speak with Omat Vastsea on the south island through the underwater tunnels.

you say "Hail, Omat Vastsea"

Omat Vastsea bows deeply. "I have been expecting you, Cashiuus. The waters have foretold your arrival. I am High Priest Omat Vastsea of the Triumvirate missionaries. Please feel free to enjoy the quiet solitude of this inn."

you say "your brother sent me"

Omat stare at you. "I received word from my brother you would be coming. I have just the task for you. I am sure you heard of the [Plasmatic Priests].

you say "what plasmatic priests"

Omat Vastsea says "The Plasmatic Priests were worshippers of Fennin Ro. Their number were all but destroyed by adventurers, and with the silence of the Pantheon they no longer draw power from the Tyrant of Fire. However they are still a danger, please find the last remnant of their order and bring me proof of their [destruction].

you say "what destruction"

Omat Vastea says "They are in hiding, the few alcoves that I managed to find were shrouded and hidden. Take this signet and find the keeper for each alcove. Show it to him and he will drop the veil. Strike fast and exterminate the camp before he is able to cloak the camp again. Return the talisman to me with proof of the deaths of the three remaining high priests. Once you have done this, I will send you to my brother with my blessings."

You receive Talisman of the Plasmatic Priests
MAGIC ITEM LORE ITEM NO DROP

Now to figure out where the alcoves are...