Eternia

Rest at the inn and spend your hard-earned money to buy some new scrolls and equipment for your party. You have to head to the central healing tower to the north. Before going there, head to the east and search the alley behind the house until you get the prompt to "inspect“. You'll get a hidden Arctic Wind from it. Now check another space behind the shops and to the left of the healing tower's entrance. There's a hidden Elixir there. Enter the healing tower to proceed with the story.

Inside the healing tower, go upstairs to continue with the story. Once done, a new party chat will be available (Three Passages to Central Command) Leave Eternia through the western exit and you'll be back in the world map.

As Edea explained, there are three paths leading to Central Command. The shortest is the central path where a mini-boss is blocking the path. This is supposedly the hardest. The boss is challenging enough; not to mention the nearby cannons will provide regular shots that will take a good chunk of your party's HP.

Tip: The Mandragoras that spawn along the paths give considerable money, experience and job points. You can grind near the town so you can afford the much needed scrolls and gears.

Central Path

Boss: Guardian

HP: 90,000 Weakness: Lightning, FAM: Inorganic

It will help a lot setting up at the start of the battle by buffing yourselves and storing up BP's. Don't go negative BP s in the battle especially if you'll need extra actions to heal up. As much as possible, it will greatly help if you have LV5 White Magic to assist you. Angelic Ward can also help minimizing the damage you receive.

The Guardian uses Rocket Punch as its main attack. Optical Camouflage increases this enemy's evasion. As you attack, the nearby cannons and artillery will deal heavy damage to your party as well so keep everyone healed up. The guardian will remove its limiter to increase its p.atk and p.def ratings so be careful not to be caught off guard with its attacks. After a few turns, it will recess its limiter, bringing it back to its default stats. Use this chance to attack it.

Before moving forth, you can return back to the city and rest up.

Western Path

This is a longer path than the central one and there's a mini-boss waiting at the end as well. There's an off-road further to the west as well that leads to the Vampire Castle. You can't enter it for now so just take note of it for now.

Dragon Zombie

HP: 25,000, Weakness: Fire, Light FAM: Undead Dragon

Don't be intimidated by its enormous size. This dragon has a much lower HP and multiple weaknesses. Aside from black magic and deliberately healing it, you can also deal massive damage using the Ranger's Dragon Slayer or Undead Slayer skill. It primarily uses Poison Breath that will deal damage and poison everybody as well as Bite, a single-target attack but deals considerable damage nevertheless. After defeating it once, it will rise up again with full HP so use the same tactics and keep your party healthy until it goes down again.

You'll get a Dark Matter and Elixir after the battle. Before moving forth, you can return back to the city and rest up.

Eastern Path

This path is the longest but at least you don't have to face any mini-boss. If you're taking this path, I suggest turning off the random battles since you'll need to be in full health before entering the Central Command. There’s a split in the road further east, leading to Gravemark Village. There, you’ll get more entries to your Encyclopedia, especially around the topic regarding the Great Plague.

There are also two hidden items in the village, search the second gravestone southeast of the hut to get a Light Curtain. Examine one of the gravestone markers near the exit of the village to find a hidden Ice Charm.

Before entering Central Command, equip your characters with Poison Immunity ability or similar accessories. Alternately, you can also equip your characters with Safety Rings to prevent the Death status effect. Head inside to trigger a scene.