You fight 3 tonberry NM's in Den of Rancor (one is a SMN that has an elemental, kill that one last and don't bother to fight the elemental, just use it as an aspir *****). There are a few things you need to do before the actual mission:
-Do the quest to get the paintbrush for Temple of Uggalepih
-Get 4 unlit lanterns (rare/ex drops from tonberries)
---With the lanterns, you only need 4 for however many people go, if you have 3 parties going to do it, you only need 4 for the whole alliance, likewise if only six people are going, you still need 4 lanterns for the party.
Edit: Here's a link to the mission description on Alla,
ZM4 Mission Description Edited, Fri Jan 28 10:31:03 2005 by Pax