A type of magical volcanic gemstone that can store magical energy for use at a time of the holders choosing. Sopstone looks like a milky white crystal, taking on different hues of colour depending on the type of magical energy it has been charged with. It has a very high capacity, and can absorb all known types of magical energy, arcane, divine or otherwise.
One of the most reliable types of 'magic battery' currently known. Sopstone does not wear down or lose effectiveness over time, and can store much more energy than other mediums used for this purpose. This makes Sopstone highly desirable by magi and spellcasters of all types. However, it is exceedingly rare and usually very difficult to obtain, making it an incredibly expensive material for all but the most successful and affluent magi.