In this quest for newbie SKs in Grobb, the NPC tells you get get undead essense, but he does not say the mob which drops its. After searching I found the mob that droped it, but it was not called undead essence, it was called minor undead soul or something. Also, you need a black ikor blood from a giant swamp leech, but I have only seen 1 giant leech in the last few days. Perhaps you could change the text the NPC says and add a lot more leeches =)