To unlock this achievement, you need 300 or more Ore. This is only possible by choosing the Iron Hunger fate when you're building your deck.
One way of getting this, is by playing the Queen of Skulls level. Compared to Endless, you have a finite number of floors, but there's a certain advantage to that: if you didn't get it that time, just try again. A single run takes one, maybe one and a half hours, tops and you'll never really have to finish the final floor anyway.
Getting gear and smelting momentum is easier, too, since you can control the cards that appear.
Make sure that you have most, if not all, of the gear from the base game, including the Dragon Relics: except for the Artifact, these items smelt for 8+ ore a piece. The helms from the Wildcard Fates are not necessary for this achievement, though if you can replace a base game helm with DLC one that gives more Ore when smelted, then by all means, do so. You'll only be using your base equipment: you'll be smelting the rest.
The only Encounter you'll really need, is the Soul Gem. This can be gotten from the Fire In The Deep encounter. You can get Fire In The Deep after defeating the Queen of Plague. The quest line is as follows:
Fire In The Deep: Choose 'Attack the creatures immediately!' and beat the golems for the token
Golem Hunting Party: have these three in your deck and beat all three parties to unlock the token
Summoned: If I remember right, you'll have to fight here to protect the summoner. Do so, and you'll get the token
Dark Crystal: I don't remember doing anything special here, either. If you have to make a choice, agree to go searching for the Dark Crystal
Dark Crystal, Pt 2: Choose to defeat the five Lava Golems
You now have the Soul Gem encounter.
Last, but not least: defeat the King of Scales. This will place small piles of gold on the map, and give you some upgrades for you to smelt at the start of the session. It also gives you the Fine Sword and shield. While not the best gear, the sword's speed will make up for the lack of special abilities.
Deck suggestion - Equipment
01. Scorching Zeal
02. Life's Limb
03. Desperate Measures
04. Undead's Bane
05. Mortal Whimsy
06. Skeleton King's Sword
08. Blood Crescent
09. Dragon Tongue
10. Kraken Claw
11. Huge Hammer
12. Emperor's Jewel
13. Dragon Shield
15. Dragon Armour
16. Occult Reflection
17. Wilderness Armour
18. Forbidden Armour
19. Depth of Night
20. Armour of Cold
21. Chains of Rage
22. Dragon Helm
23. Clairvoyant Helm
24. Fate's Folly
25. Helm of Reflection
26. Oracle's Diadem
27. Mercenary Contract
28. Consuming Shame
29. Lightning Crash
30. Folded Steel
31. Spirit Walk
32. War Cry
Don't put in any rings: you can't smelt rings and they take up precious space. Every single piece of equipment listed should give you 7 or more Ore when smelted.
Deck Suggestion - Encounters
01. Soul Gem: Required! Removes a random curse for 5 food
02. Battle Practice: usually gives gold upon completion
03. Desert Cult: You could combat for Gain cards
04. Noble Trader: you could sell an item that gives a low amount of ore for decent gold
05. Field of Poppies: only useful if Metal Ore and Field of Poppies are on the same level. Allows you pick up Metal Ore twice for 150 ore
06. Marketplace: sometimes, you can sell your food.
07. Treasure Chest
08. Summoned: the combat usually gives a few gain cards
09. The Maiden: ask for gold
10. Metal Ore
11. Desert of the Damned: sell the coffin
12. Trading Post: you could trade food for some gear
13. Loan: Usually gives you more than you put in
14. Shop: Gives goodies when you land on it. Do not buy from this shop
15. Devil's Choice: usually an easy combat, gives Gain cards
16. Tavern Wager: bet for gold, hope for more gold
17. The Kraken Unleashed: smelt the mask
18. Cave Rescue: kill the pirates for Gain cards
19. Cave Shelter: charge in there and kill the bad guys for goodies
20. A Winding Trail
21. Angry Guild Master: steal from him
22. The tavern: help him find the ship: you might get some good stuff. Don't kill him, but share the treasure to prevent getting 3 curses / pain cards
23. Stranger in the Shadows: try to get as much gold out of this as you can. There's a 25% chance of failing so you have excellent odds for 10 gold per bite
24. Sunken Treasure: can net you ore or gold, but it's a bit of a gamble. You have five attempts, more if you find mermaids
25. Dead King's Hall
26. Maze of Traps
27. Battle at Brooktop
28. Deadman's Gorge
29. A Merchant's Favour. You can go either way: gear to smelt or 100 gold at the cost of 50% max health.
30. Ghost of the Sea: use the dashboard trick until she gives 25 Ore
31. The Crucible: might give you some cash *
32: Wife's Fury: gives gear
* If you have the Royal Treasury card (obtainable from the Warlord Fate), you can use that one instead of the Crucible. There's a 25% chance for 100 gold and two pieces of equipment, which is better than the results of the Crucible. If you fail, you can always use the dashboard trick. Thanks to BOLD GAMER for the suggestion!
As I mentioned: you'll be playing the Queen of Skulls. This level has two curses:
1. Haunted: every time you buy an item, you'll get a curse
2. Merchant's Guild: all shops offer items at a cheaper price
The basic idea here is to amass as much gold as you can and to buy out the dealer's shops every chance you get. The curse does NOT count for the Shop you put in the deck: this shop offers the items at the usual price. Only shop at the dark blue tinted shops because only these shops have reduced prices.
To prevent getting thoroughly cursed, you have to encounter the Soul Gem and use food to remove a random curse. Use the dashboard trick until it removes the Haunted curse. You can now buy items freely at reduced prices. Smelt everything you buy and you'll get a lot of Ore, quickly. Prices are around $20 per piece of equipment.
When you find Metal Ore you'll get 75 Ore. If you're really lucky, you'll have a Field of Poppies on the same floor, which will allow you get Metal Ore twice, netting you 150 Ore.
If you're lucky, you might be able to buy the Mercenary Contract artifact. If you do buy it, use it four times in crowded combat to gather some extra gold. I managed to collect an extra 100 gold in a single battle this way.
If you encounter Loan and he requests 10 or 20 Gold, give it to him. With such low numbers, the returns are always good.
Most of the cards in the encounter deck either give you Gain or Equipment cards immediately, or give you combat situations which, in turn, give you Equipment or Gain cards. More gear means you'll need less gold. There are some cards in there that are gambles, such as Sunken Treasure. It might work out, it might cost you gold.
Also, use the dashboard trick liberally to cross the map cheap as you can. For instance, when you get the + shaped map, you can, theorically, reach the next floor in a single step. It'd be a shame if you needed all seven steps just to reach the exit.
Also, the Ring of Hindsight allows you to see the entire map when you find the exit, so if the game reveals an interesting encounter upon reaching the exit, you can dashboard out, quit, reload and do that encounter before you move to the next floor, saving you some ore.
On larger maps, you'll have to make a decision: is the detour worth the Ore cost and the potential Gold / Ore gain? Metal Ore is always worth the detour, but for every other situation, you'll have to make a decision.
Same goes for the maps which force you to make a choice because the exit could be down or left, or up or right. I tend to pick the shortest path first, unless I know the exit isn't there (e.g.: there's a shop there). If the last encounter is not the exit and it's not helpful, then I dashboard out and start going in the other direction. This saves two steps.
Other maps have a single encounter left and down, but the path continues to the right. In that case, check the left encounter. Does it give you gold or gear? Great, grab it and check the bottom encounter. Is it useless? Then dashboard out and check the bottom encounter and skip the left one. Do the same with the bottom encounter, then continue your path.
Don't fight the Queen of Skulls, as that will end your run.
Last, but not least: you can attempt this without the Soul Gem, but there's a chance you'll get the Midas Curse. This will immediately turn all your Food or Iron Ore into gold. You might also get Haunted a second time, which will give you two curses per item, which in turn increases your chance to get the Midas Curse.