Another WTF moment from Tomb of Annihilation:
As a reward, each character will be allowed to take twenty 1-pound ingots of refined adamantine from the forge.
Hrakhamar section, page 60
Now, in the adventure's defense, adamantine trade bars has no official 5e value. And gold is essentially worthless anyway - in an adventure where there's an official countdown of only 70 days or so, I don't expect anyone to take
any downtime activities at all.
But of course those are two exceedingly weak arguments.
Most sources I can find put the value of a one-pound bar of adamantine at somewhere between 300 gp and 400 gp, so that's 6000 gp per character minimum. Not game-wrecking by any means, right?
But that assumes 1) Sithi Vinecutter is around to stop them from looting and 2) they don't just kill or incapacitate or simply ignore her. The adventure does after all only put four weak CR 1/4 creatures between the party and all the loot.
But it gets worse.
(Now remember, one of my players is of the kind that breaks copper doors free and calculates the iron weight of weapons, all in order to make a few extra gold pieces)
The smaller pool contains molten adamantine, not silver.
Hrakhamar section, page 61
Okay, what would a quick estimate by your regular friendly non-physicist Dungeon Master that haven't really thought about what appears to be a minor detail be?
Let's go with "it looks like the pool is 10 ft by 5 ft. Since the game grid is in 5 ft increments let's say the pool is 5 ft deep too".
That's a serious error right there. Can you immediately see why?
The why is because 10x5x5 means 250 cubic feet of molten adamantium. Doesn't sound so bad? If this makes 250 ingots it's about ten times the wealth, and so we'll say the molten metal is "low grade" and at 10% purity.
Still sounds reasonable?
Wrong.
The density of iron or silver (comparable metals in the real world) is 491 and 655 lbs/cu ft, respectively. That's just a number, right.
Well, if we eyeball adamantium at 500 lbs per cubic feet, a nice round number, that works out to be over a hundred thousand ingots (250x500=125000).
Even at 10% purity that would still be worth almost four million gp!!
If you have taken even the slightest step towards allowing characters to do something useful with their wealth (perhaps using the "Buying a Magic Item" rule of XGE), this location alone means they get to buy "all of it", regardless of power or rarity.
Yes, all of it.
The author would be well advised to read up on the value and density of precious metals before he writes an adventure again.
Luckily I was forewarned (remember the bit about carrying copper doors, I was not kidding), so I understood the danger before I handed out millions of gold for free.
I ended up having to change the molten metal from adamantine to electrum (another D&D metal, roughly ten times less valuable), and also lower the purity to only a fraction of one percent, and also choosing a much shallower pool. In the end, the players could spend a few days hammering out electrum ingots to a value of 7500 gp in total.
Moral of the story: don't trust game writers to have any inkling of scientific matters
