Brimstone

Brimstone (BR), also called sulfur, is a reagent that is in use on Pagan. It is a yellowish material harvested from the vicinity of an active volcano, which is easily infamable.

Pagan
Unlike the Sulfurous Ash used in the magic systems of Britannia and the Serpent Isle, which is the result of incinerating the brimstone, this is the raw form of the material and it was, because of how volatile it is, used in the magic school of Sorcery. Brimstone was used to greatly increase the power of a spell.

Trivia

 * Adding brimstone to create a spell where it isn't used does have bad consequences. It will cause a huge explosion that destroyes the candles and focus, in the process seriously injuring the Avatar.