First, 
meet Roberia at the bottom of the right tower in Ludus Lake, then ask her for the task.Physical Part of the Test
Go Back to Ellinia and meet "Grendel the Really Old" at the Magical Library (located at the top of the city). Then, ask for the test. After, go to the Dungeon (to the right where the zombies are) and find the "Door of Dimension." One that looks like a portal. After going through, you will face the other "Grendel the Really Old". Then, fight him to death. Some monsters "Tauromacis" looking like at the top will come out. After beating (other) "Grendel the Really Old" and got the Black, bring it to (real) "Grendel the Really Old" and you will get the Necklas of Strength. Then, bring it to Roberia back in the bottom of Ludus Lake and give it to her. Then, she will give you the Dark Crystal for the mental part of the test.
Mental Part of the Test
First, find Holy Stone in the bottom of the tower in Ludis Lake (so where the Yetis are). Then, answer these series of questions. You must give the Dark Crystal as sacrifice.
1. Q:Which of these pairings of the moster/leftover is correctly matched? A:Stirge - Stirge's wing
2. Q:What is NPC's will you not see in Perion in Victoria Island? A:Francois
3. Q:Which of these NPC's is the fater of Alex the runaway kid, whom you'll see at Kerning City? A:Chief Stan
4. Q:Which of these items will you receive from the NPC after collecting 30 Dark Marbles during the test for the 2nd job advancement? A:The Proof of a Hero
5. Q:Which of these pairing of jobs/required stat matches for the 1st job advancement? A:Bowmen - Dex 25+
If you get of these questions wrong, you don't have to worry. You can always start the quiz again until you get it.Then, go back to Roberia, and you get the 3rd job!!!
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