By making use of your miraculous discovery, you are able to proceed onward to Nabaath Areng.
This quest is available if you have completed the quest Have a Heart.
Starting the Quest
Talk to Magnus in Amh Araeng to begin the quest. There will be a cutscene.
Speak with Minfilia
Go east along the tracks until you can go north, and then northeast to where the orange arrow is pointing in the minimap. Talk to Minfilia to proceed.
Speak with Magnus
There will be a glow around Magnus, indicating an instanced battle. Check on him and there will be a cutscene, and then the battle will ensue.
Solo Duty: Full Steam Ahead
Your hotbar/crossbar is replaced with a small number of actions. Use Solid Barrel Combo to do a single-target attack on the enemy. Use Rough Divide to rush to the target and do a single-target attack. Use Nebula to temporarily reduce the damage that you take. Use Soothing Potion to restore some HP. You can use it every 30 seconds. Use Smackdown to increase accuracy and damage dealt. Sort Pet Hotbar allows you to change the order of these actions.
Throughout the battle, use Smackdown and Nebula whenever they become available.
Start by using Rough Divide to rush to Ran'jit, then use Solid Barrel Combo repeatedly.
When Ran'jit starts casting Shattered Sky, use Nebula to reduce damage. Shattered Sky deals unavoidable damage. Use a Soothing Potion afterward to restore some HP.
Hot Pursuit causes multiple circle attack markers to appear, one after the other. Keep moving away from them to avoid the attack.
Nexus of Thunder creates line attacks in a + pattern from the middle of the area, followed by another set of line attacks at an angle from the first. Stay out of the attack markers to avoid the attack.
Afterward, you will be knocked back and stunned by Ran'jit's dragon familiar. Move out of the ensuing attack markers as soon as possible.
Ran'jit will sometimes cast Coiled Levin, creating a group of circle attack markers that turn into electrified puddles. Avoid standing in these puddles. Since Ran'jit's dragon can knock you back, avoid being between the puddles and the dragon to avoid getting knocked into the puddles.
Eventually, Ran'jit's dragon will move to the side of the area and knock you back to the far side, and there will be a cutscene.
Ran'jit will cast Unceremonious Beheading, a large circle attack centered on Ran'jit. Move out of the attack marker to avoid it.
Merciless Left is a large cone attack from Ran'jit that hits the area to his left, soon followed by a cone attack that hits the area to his right.
When Ran'jit dashes to the side and begins casting Katun Cycle, use Rough Divide to rush to him. Katun Cycle is a donut attack where the only safe area is near Ran'jit.
Ran'jit will create four untargetable Serpent Heads that all target you with the line attack Snaking Flame. After some dialogue, you will be able to use the Duty Action Perfect Deception. Use it as soon as it becomes available.
While Perfect Deception is in effect, Ran'jit will cast Evisceration, a large cone attack. Stay out of it.
When your duty action changes to Shining Blade, avoid all attack markers and get close to Ran'jit, then use Shining Blade.
As the battle progresses, Ran'jit will attack with Merciless Left or Merciless Right at the same time as Nexus of Thunder. Nexus of Thunder hits first, so get out of the line attack markers before you move out of the cone attack markers.
Eventually, Ran'jit will summon more Serpent Heads, and the Perfect Deception Duty Action will become available again. As before, use it as soon as it is available, then dodge attacks and get close to Ran'jit to use the Shining Blade Duty Action as soon as possible. Note that you can't use Rough Divide while concealed, so you will need to move quickly if Ran'jit casts the Katun Cycle donut attack.
The next two times that you try to use Perfect Deception, Ran'jit will hit you with unavoidable attacks. Afterward, you will sometimes be immobilized and unable to avoid some attacks. Use Soothing Potions as needed and be sure to keep using Smackdown and Nebula whenever they become available.
Eventually, your Duty Action will change to Souldeep Invisibility. Use it as soon as possible, then dodge all attacks and get close to Ran'jit to use the new Duty Action, Leap of Faith. There will be a cutscene.
Speak with Minfilia
Talk to Minfilia to complete the quest.
Next Main Scenario Quest
After you complete the quest, talk to Minfilia to accept the next quest: Crossroads.