does anyone know where you get doomtrains card?

first you have to win the Alexander card from Piet on the space station. If you're past the space station you have to find the crash site where Piet's escape pod landed. It's not marked on the map, you just have to search the area until you find it. Search the peninsula of the Abadon Plains south of the Esthar region.

During the Queen of Cards side quest you have to give her cards she asks for by losing them to her in a game. When she asks for the Alexander card her artist father will create Doomtrain. To find Doomtrain, you have to go to the pub in Timber and talk to the man behind the counter in the right corner. Talk to him, don't challenge him to cards. He'll challenge you. Beat him to get the Doomtrain card. If he doesn't use the Doomtrain card keep playing until he does.