Tip: Do this quest as early as possible after changing to Thief as the given experiences will help you level up immediately which lessens going back & forth to the NPC.
1. Talk to the Thief Trainer next to the entrance to the Morroc Pyramids dungeon (Yierhan moc_ruins 66, 164). After asking him about training, he quizzes you on which stat is most important for damage. Answer: STR. He then asks you to learn some new skills.
2. After getting at least one job level, add the skill point to any of your skills, and then talk to Yierhan again. He'll explain how the skill(s) you got work, and will offer to explain how others work as well. After telling him you know enough, he'll give you some Base and Job Experience. He then tells you to learn some more skills, and come back after.
3. After learning at least one more new skill (or adding one more point to a skill you already have), talk to Yierhan again. He'll send you to south of Morroc (moc_fild12), and tell you to collect 10 Feather of Birds.
4. After collecting the feathers, go back to Yierhan (he doesn't take the feathers), who will give you some more Base and Job Experience and a Main Gauche.
5. Talk to him again, and he mentions a fight that took place south of town, noting that an Assassin may have taken part in it, due to traces of poison left at the scene. He sends you off to investigate, giving you some more experience.
6. Go to the map south of Morroc, (moc_fild12), and right below the portal to town is the first "Trace of Battle" (166,369). Talk to it, and it tells you about the trail, which leads south.
- Note: To avoid having to backtrack, make sure you click on each of the Traces until they repeat which direction the battle went.
7. Further south on the same map, find the second Trace and talk to it (173,215). It says the trail continues to the east.
8. Next to the east portal on the same map, find the third Trace and talk to it (276,165), where you see some footprints.
9. Head through the portal to the next map (moc_fild11), and locate the Trace next to the portal (39, 163), and talk to it. Apparently someone else joined in the battle here.
10. Go towards the south portal on the same map, and talk to the fifth Trace (205,52). You need to neutralize the remaining poison here with a Green Potion. After neutralizing it, investigate, and recover a piece of cloth.
11. Head north to the top of the map, near the portal, and talk to the next Trace (184,342), which says the footprints are definitely heading south.
12. Go through the south portal to the next map (moc_fild17) and talk to the trace just south of the portal (213, 358). Only two people were involved in the battle from this point on.
Notice: moc_fild17 has Lv. 30 Frilldoras and Lv. 34 Sandmans
13. Farther south on the map (228,274), talk to the next Trace, which says the battle continues westward. Keep talking to the trace until it repeats this message.
14. Near the west portal, talk to the Trace (34,291), which says the combatants grew increasingly desperate at this point, and the trail heads west.
15. Enter the west portal, and in the next map (moc_fild18), go west from the portal until you see the Trace near a tree (346,296), and talk to it. Someone began bleeding here, so the trail will be easier to follow.
16. Walk southwest until you see the next Trace (309,257). The pursuer got closer to their prey here, and the trail heads north.
17. Below the north portal (177,333) is another Trace, which says the trail turns southwest.
18. Go southwest and talk to the Trace at (111,303). More people joined in the battle, and the trail goes south.
19. Farther south is the next trace (109,197). Investigating, you use another Green Potion, but nothing happens. You must have a Red Gemstone and Green Herb in order to clean up the poison, and you find another piece of poison stained cloth.
20. At the bottom end of the map (156,96), talk to the last Trace. One set of footprints leads off the cliff, while the remaining head back out. Whoever was being pursued was apparently finished off.
21. Head back to Yierhan, and report on what you found. He rewards you with some Base Experience, a lot of Job Experience, 5,000 Zeny, and a Mantle.
- Credits to respective content owners.