Doomtrain GF (Guardian Force)
Doomtrain is a Guardian Force that you can create once you have acquired all the necessary raw materials. The last and most important piece is the Solomon Ring, which you can only obtain after you can travel to Tear’s Point. This timing in the game means that you can’t obtain Doomtrain until you reach this section of the game:
30) Lunar Gate / Tear’s Point / Lunatic Pandora
Walkthrough Guide

Exiting Esthar on the way to Tear’s Point and then the Lunar Gate to get on the Lunatic Pandora.
If you missed having the raw materials on hand, though, you can always come back after you have obtained the Ragnarok from this portion of the game:
33) Ragnarok and Final Preparations
Walkthrough Guide

The final preparations for the end of the game and rescuing Rinoa from the Sorceress Memorial.
There are four items in total that you will need to obtain to create Doomtrain. They are:
Solomon Ring
Malboro Tentacle (x6)
Steel Pipe (x6)
Remedy+ (x6)
For more information on how to obtain these items, read more below.
Solomon Ring
The Solomon Ring is the easiest of the four items to obtain. Just travel to Tear’s Point any time after you complete the events following your first arrival at Esthar and pick it up near the center of the monument.


Malboro Tentacles
You can obtain Malboro Tentacle by defeating or using
Mug on a Malboro or by refining
Malboro Cards into Malboro Tentacles. The Malboro Card route can be a time-consuming venture, depending on how much Triple Triad you’ve been playing up to this point. The real kicker is that you will need at least 24 Malboro Cards if you need a full 6 Tentacles, as the conversion rate for the cards is 4 cards to 1 tentacle.
Alternatively, you can seek out and engage a Malboro out in the open world.
There are three spots where you can find a Malboro: the first and second are on the Island Closest to Hell and the Island Closest to Heaven. These are two islands where you can find high-level monsters, but you can only reach these islands after you have obtained the Ragnarok (completing the Ragnarok section of the game).
Check out the Island Closest to Hell / Heaven page for more information on where to find them:
Island Closest to Heaven & Island Closest to Hell
Side Quests

Details on the locations of the two islands, what you will find there, and the Magic you can Draw from enemies while you are there.
You can also find Malboro enemies hanging out just outside the Chocobo Sanctuary in the Grandidi Forest north of Esthar. You will need to travel by Chocobo from the northern continent to reach this area, but once you get to the forests outside the Chocobo Sanctuary, wander around until you eventually run into one. Speaking of which, you should definitely prepare yourself for this fight…

Preparing for Battle Against a Malboro
Fans of the Final Fantasy series are likely already familiar with the challenges associated with fighting a Malboro. This enemy has caused many “Game Over” screens for players that are not prepared. The biggest obstacle for you to overcome is dealing with Malboro’s negative status effects, but there are some strategies you can use to overcome this.
Make sure to junction status Magic to your armor to negate as many of these status effects as you can. Ensure that one character can protect themselves against Confuse and
Berserk, as these are the two most challenging abnormalities to deal with.
From there, as long as they have access to use an Item and/or cast Magic, they should be able to heal the other party members after Malboro uses Malboro Breath.
Most importantly, though, make sure you save before you engage in battle with one!

Steel Pipes
The Steel Pipes are a lot easier to obtain compared to a Malboro Tentacle. Travel back to the forested area near where Galbadia Garden was located (before it flew away) and search for an enemy called a Wendigo. Each Wendigo you defeat has a chance to drop Steel Pipes.


Remedy+
The last items to obtain are leveled-up versions of a Remedy. You will need to have a total of 60 Remedy items in your possession. Then, use Alexander’s
Med LV Up ability to convert them to a
Remedy+.
Remember that if you don’t have a specific Guardian Force ability, you can earn easy Ability Points by traveling to Cactuar Island. For more information, visit the link below.
Earning Fast Ability Points (AP)
Tips and Tricks

Traveling to Cactuar Island to quickly level up your Guardian Forces, earn then a ton of Ability Points, and have them learn all their Guardian Force abilities.
This is everything you need to know about creating Doomtrain. Congratulations on creating your new Guardian Force!
Doomtrain
Achievement/Trophy
You will receive the Doomtrain Achievement/Trophy once you have successfully created Doomtrain using the raw materials noted above.

Assuming that you navigated to this page as soon as you reached Tear’s Point, use the link below to head back to the walkthrough:
30) Lunar Gate / Tear’s Point / Lunatic Pandora
Walkthrough Guide

Exiting Esthar on the way to Tear’s Point and then the Lunar Gate to get on the Lunatic Pandora.
(or if you completed this later on in the game, return to the Ragnarok section below)
33) Ragnarok and Final Preparations
Walkthrough Guide

The final preparations for the end of the game and rescuing Rinoa from the Sorceress Memorial.