The core of the idea is that you’re still going to use whatever magic items you find rather than customizing your items to exactly the thing you want. When you have items that you really sincerely don’t care about – say, attunement items beyond (3 * party size) – you pulp them for other major, campaign-altering projects, whether that’s building your extradimensional vacation home or stopping the progress of a world-rotting curse.

However, I do like residuum from a worldbuilding perspective. 4E had some great imagery regarding mining astral diamonds, turning the corpses of dead gods into mines – think Knowhere from Guardians of the Galaxy 1. With zero effort you can make it so wizards are combing the astral sea to create residuum refineries to create ancient items. Imagine a Githyanki raid led by an adult red dragon on the Ifrit Sultan’s residuum mine.
I once had it so residuum was left behind by magical catastrophe and there were stretches of residuum sands like the tar sands in Canada which people would often fight over.

It also answers an important question about making magic items in 5E “Who the hell spends 5 years making a Horn of Blasting?” or at least, who spends massive amounts of time and money to make the more dangerous/less useful items. Making these items doesn’t take half as much time and effort with a vial of residuum – or, alternatively, “dirty” residuum can cause imperfections in magical items leading to items that explode or demand blood to work or all these other weird and frustrating inconveniences.

I may bring residuum to the world I’m making in 5th edition, just keep it out of the hands of players.

I don’t mind it as long as it doesn’t hijack the story, but a little monster hunting turns out to do a good job to make for some nice side treks. It also means that there are some nice random fluctuations when buying things like healing potions.

I love this. Thanks for sharing.

our campaign is heavy on dragons and he really wanted to do this… so it works. But I’m not playing monster hunter for magic ingredients in any game I run.

I’m wary of using “monster drops” as magic item components, lest it encourage a “grindy” attitude in players. Using the search for rare components as an adventure hook is great, but I don’t want to give my players any extra incentive to indiscriminately slaughter monsters by the dozen.

It annoys me to no end when players have a blase attitude to magic items. In a campaign I ran a few months ago, I created a sentient weapon. I “intended” it for the fighter, as they were the only one without a native magical attack. Instead, the fighter nonchalantly handed it to the blade pact warlock, saying he’d “get the next one.” This attitude annoyed me to no end, so I decided that the sentient weapon would be personally offended that the players didn’t fight over it. The weapon began to plot ways to trick the players, eventually trapping them in the Astral Plane. The players escaped, and vowed revenge.

The rivalry between the players and the sentient weapon eventually became the centre of the entire campaign.

Yep! I’m making him work for it 🙂