Instructions
Go to the Zertinian Caverns to find Andrammelech. Reach at least level 40 before attempting this, and make sure you have strong ice magic as this is the only magic this flying Esper is vulnerable to. Access the caverns from the Ozmone Plains or Dalmasca Westersands. Find the Esper in the southwestern portion of the caverns.
Do the mob hunts "Waterway Haunting" and "Lost in the Pudding." Use the resulting sluice gate key to turn on the waterway controls in the Garamsythe waterway. Navigate your way through the waterway puzzle until you can open and enter the No. 1 Cloaca spur where you must fight and defeat Cuchalainn.
Obtain the Barheim Key through doing the Desert Patient quest in the desert. Then, travel to Estersand and locate the secret passage which will eventually lead you to Terminus No. 7. Travel south down the Zeviah Span until you run out of road, then push over the obstacle to access the West Annex which you must follow until you fight Zalera. Make sure you always kill the monsters Zalera summons quickly, otherwise the Esper is immune to your attack damage.
Visit the Empyrean seat in the Mosphoran Highwaste. Go to the Babbling Vale and speak to everyone you can. Now, throughout the surrounding areas you need to touch the Shrine of the South Wind, West Wind, Northwest Wind and the Weathered Rock. Go back to the Empyrean Seat to fight Exodus. Dispel Exodus to make him vulnerable and save magic for the end of the fight when he will become invincible against regular attacks.
Complete the portion of the main quest that occurs at Mt. Bur-Omasace and then visit the acolyte at the entrance of the temple. Take the item he gives you back to the Stillshrine of Miriam and visit the waystone in the first room to travel to the Zeromus fight. Prepare yourself for a purely physical fight, because you can't use magic in this battle.
Complete the "Crime and Punishment" hunt and then go to Lowtown. In Old Dalan's house you must talk to Roh'Kenmou. From there, talk to Deeg and follow the prompts and hints in the quest. You must follow the quest along until you gather a Dull Fragment from the waterway, the Blackened Fragment from the "Crime and Punishment" Hunt, the Grimy Fragment after talking to a series of NPCs in lowtown and the Moonsilver Medallion from Otto in Old Archades. Travel to the Necrohol of Nabudis and fight your way through until you face Chaos.
Travel to Giruvegan and the Great Crystal to find and capture Ultima. Travel through the waygates until you have activated the Scorpio, Sagittarius, Gemini, Leo, Capricorn and Virgo gates. Travel through the area and up the left path from Virgo to find Ultima. Cast dark magic as often as you can because Ultima is vulnerable to it.
Talk to Yugelu in Jahara after you have collected at least 10 espers and completed the hunt for the Catoblepas. Travel to the Henne mines special charter dig area, which is now accessible, to face Zodiark.