Bloodcrystal (concept)
Named for both its striking crimson hue as well as the incredible amounts of human losses needed to mine even trivial amounts, Bloodcrystal has consistently been one of the most expensive, rarest and sought after commodities known to man. With the number of locations harboring deposits countable on the fingers of one's hand, and staggering casualty rates among those unfortunate souls sent to extract it (usually slaves), even lesser mines of the mineral have had wars fought over them.
Incredibly magically potent, they are usually most desired by and effective in the hands of Living Magi, though no Magi of another school would turn down the opportunity to obtain one, either. In Aversaria, the chief source were the mines of the northern fringes of the Empire, taken from the Chevalien centuries ago.
The locations where it has been found are, without exception, extraordinarily hazardous. The chief killer in these wretched deathtraps is the powerful background Magic that rapidly causes Exposure Sickness and death. Efforts to locate the source of this phenomenon have all met failure.