Before getting into the detail, getting this achievement can take a while. It's all RNG based so you could get lucky but just prepare for a long haul.

Now Broken Geography requires you to "Place 10 cards you didn't have in your deck, not counting ^Oblivion^". The only way to do this is through the enemy Prime Matter who's ability Creation give you 3 random cards (with a 33% chance of dropping a gold card).

This is where RNG starts coming into play. Prime Matter is an enemy that has a chance of spawning from a defeated Ghost of a Ghost, which has a chance of spawning from a defeated Ghost, WHICH has a 20% chance of spawning from a defeated enemy with a soul near a battlefield. Oh, and Prime Matter's ability can still give you cards that you already have in your deck.

Now you know why this achievement is so rare.

For this we'll be focusing our deck around the Necromancer class. You can use the other classes, I just like the skeletons.

For sure you want to keep Battlefield and Grove.

• While it's not displayed here, Vampire Mansions are also a great card to have as Grove enemies max out at 4 stacks. Having a vampire mansion allows a fifth spawn (with a soul) giving you another chance at a ghost spawn. (Thanks MekanikStik!)
  
• Using the minimum amount of cards needed means a bigger chance of getting a new card.
  
• Avoid using blood grove as it doesn't technically kill any enemies so it won't spawn ghosts.
  
• If you're using Warrior or Rogue you can replace Smith's Forge with Outpost.
  
• Landscape cards can be changed around depending on your class as well.
  
• Ancestral Crypt can be switched with Arsenal.

For this to work you'll need to play on Chapter 2+ so Prime Matter has their Creation ability. Personally I did this on Chapter 4 since there's no limit on resources.

Now for placement you'll want to place as much groves as possible, with the battlefield overlapping the groves. Keep in mind that overlapping battlefields does not increase the chances for ghost spawns, it unfortunately stays at 20%.

For traits just aim for the best ones you can get, but if you can grab "Card-Sharp" which gives you a "10% chance to keep the card after placing it". While 10% doesn't seem like much, it still gives you an extra chance to place your non-deck cards again if it triggers. Note that this doesn't work for gold cards). (Thanks Alberny!)

Also remember to leave extra space for landscape, roadside, and road cards (4 spaces should be plenty). You won't know what cards you're going to get and you might be like me and not have enough space to place a Treasury card. (Thanks Jojabi!)

The rest is really just updating your gear and waiting for the RNG to fall into your favour.

Happy Looping!