Basriel is a mist-born deity that indirectly influences certain aspects of Maradul, though they are essential to much the realm's function. Put simply, Basriel is a force that attributes value to certain objects, actions, knowledge, and whatever else may exist. Though this assignment of value, spells, trades and the like have a sort of unrelenting baseline to form the power of their actions over. As certain actions change the balance of Maradul, Basriel will so too change the worth of certain things. It is due to the existence of Basriel that magic may not spontaneously create value, and instead can only transmute something valuable from something of equal value. Value seemingly lost in transmutation is known as Basriel's Tithe, which is considered the price of the act of transmutation itself.
While the calculations of absolute worth may seem daunting, in truth they rarely matter for those outside the realms of worldwide trade or magic. The exception to this is vying for the Boon of Basriel, which can be acquired based upon a sacrifice of wealth to the god. The wealth sacrificed to receive this boon must be in proportion to the total wealth you control, meaning the rich must sacrifice more, but what you may ask of Basriel can be greater as a result. The supplicant can specify the nature of the boon they wish to receive, and their wealth will only be sacrificed if Basriel "agrees".
There are some, such as the The Keepers of the Golden Sky, that do not believe in the existence of Basriel and instead purport that these edicts of value are a result of the designs of Sevantus.