Rune Caster Guide

Images taken from: http://www.inven.co.kr/board/powerbbs.php?come_idx=4185&l=6761
Slowly adding in iTOS images taken by myself.

1) Talk to the Old Man NPC in Fedimian until dialog is mentioned about a female mage looking for stones engraved with glowing blue characters. (http://i.imgur.com/CeFzq8X.jpg and http://i.imgur.com/xcfK26m.jpg)
2) Go to Mage Tower F1, next to the Vakarine Statue. There are books scattered about this area (http://i.imgur.com/Et7KAEl.jpg), read them all. One book is sealed with a spell, which will release upon reading all the other books. (http://i.imgur.com/TDZWv3F.jpg; http://i.imgur.com/45gESLs.jpg) Reading this mentions Goddess Saule.
3) Talk to Goddess Saule in Septnyi Glen, she will give you some guidance about rune stones. She mentions she felt something similar in the Royal Mausoleum. She also mentions it might be worthwhile talking to some humans, like the Jonas family or people who have been living for long periods of time. (http://i.imgur.com/BYUiaNY.jpg; http://i.imgur.com/Wxs9NF4.jpg; http://i.imgur.com/NEnFmJQ.jpg)
4) Talk to Ahylas Jonas at Gateway of the Great King, he will give you the Rune Stone of Ice. (http://i.imgur.com/BT98BtE.png)
5) Go to Royal Mausoleum. Each floor has a specific area to where the Thurisaz Rune can spawn, and seemingly is on a respawn timer of 30 minutes to 1 hour. (Eg; 5F Rune Location: http://i.imgur.com/EnhdydT.jpg) Below are the co-ordinates on each floor for the Thurisaz Rune:

1F; [X: 649, Z: -1028] (http://i.imgur.com/mjRuLpm.png)
2F: [X: -860, Z: -784] (http://i.imgur.com/9GVJlTg.png)
3F: [X: -1046, Z: 144] (http://i.imgur.com/G90iRjO.png)
4F: [X: 477, Z: -1484] (http://i.imgur.com/t0uPxCu.png)
5F: [X: -3062, Z: 316] (http://i.imgur.com/KcEJ2Ev.jpg)

6) Go to Nuoridan Falls, and find the Hagalaz Rune behind a Stone Monument. (http://i.imgur.com/Y39GkwW.jpg)
7) First, talk to the Dievdirbys Master in West Siauliai Woods, he will mention feeling runic power in a sealed place in the woods. (http://i.imgur.com/54weZBN.jpg) Use the Seal of Space to enter the hidden grove and find the Algiz Rune. (http://i.imgur.com/RWIedk9.jpg)
8) Talk to the Chronomancer Master at Stele Road. She mentions that she was given a rune stone as a child, but may need to find it. However, she will eventually find it and give it to you. [Note: People have said she might not give it to you straight away, however I got it instantly. You may need to wait a while and talk to her again later.] (http://i.imgur.com/WvHKNLd.png)
9) Once you have all 5 Runes, right-click any Rune in your Quest Inventory to fuse them into the 'Rune Caster's Invitation'.
10) Go to Goddess' Ancient Garden with the Invitation and find the Rune Caster Master, who is now visible. (http://i.imgur.com/6356lJk.jpg)

Congratulations! You can now advance to Rune Caster at Rank 6 Wizard, no prerequisite jobs required.