Arcana is the source of energy that powers ‘magic’ in the more traditional sense, in particular the spells cast by Mages of all kinds and in many (but not all) kinds of rituals.

Arcana is present in every part of the universe, albeit in greater or smaller quantities in different locations, and it acts as a strange invisible liquid, with currents, ebbs and flows. Though never acting quite in the same way, it is influenced by the material world both on the small and large scale, and certain patterns in specific materials can draw it in, while others push it away. Interestingly, Arcana also reacts to the intent of those in the area.

Arcana interacts with all other forms of energy, not just the four other mystical kinds, and electromagnetism in particular gets affected in very odd ways. Many refined forms of Arcana exist, and it seem to exist more on a spectrum than with clearly defined boundaries between one form and another.