Doomtrain required getting the Solomon Ring, and using it after you've obtained:

  • Steep Pipes, x6
    - Steal from Wendigo, right outside of Galbadia Garden.
  • Malboro Tentacle, x6
    - Junction "Initiative" and "Mug" to a character and go hunting for Malboro.
  • Remedy+, x6
    -Buy 60 Remedies and use Med LV UP to turn them into Remedy+.