Doomtrain Card - FF8 Guide
Location: Timber Pub
NPC: Timber Pub Owner
Card Mod: 3 Status Guards
First Available: Disc 3
The Doomtrain Card is both used in and won as part of the Queen of Cards Side Quest and in order to get access to this card, you'll need to complete a majority of that quest first. After losing the Alexander Card to the Queen of Cards you'll be able to win the Doomtrain Card from the Timber Pub Owner (pictured above).
In addition to the Doomtrain Card being unlocked through the Queen of Card Side Quest, in order to win the final card of the quest, Phoenix Card, you'll have to lose the Doomtrain Card to the Queen of Cards. Basically that means don't Card Mod it until you've completed the quest.
Unlike all of the other Rare Cards, you can't win the Doomtrain Card from any of the Card Club Group onboard the Ragnarok during Disc 4. Every card that's a reward in the Queen of Cards Side Quest is unique and can't be acquired any other way.
After winning the Doomtrain Card back from the kid in the Dollet Artist's House you can safely Card Mod it into 3 Status Guard items. The Status Guard item teaches a GF the ST-Def-Jx4 Ability which allows you to Junction 4 magics to your defenses against status magic.
This is an insanely useful item and one you'll definitely want to teach to at least one GF. Only two GFs learn this ability naturally, Cerberus and Doomtrain, which will leave one person in your party without it. Below you'll find some of the GFs I recommend teaching this too, as they're not commonly paired with either Cerberus or Doomtrain.
GFs to use Status Guard on: Siren, Brothers, Leviathan, Tonberry