Mana is a universal substance that is the source of magic. It exists in at least some capacity everywhere in the known cosmos, but it's unevenly distributed. Though it's a very important material, it can also be very dangerous in high quantities.

Mana exists in three primary states:

Mana gas is the most common. It's typically not visible to the naked eye, and is present in some measurable amount basically everywhere. This is what's most commonly used for spell-casting, as casters can pull it straight from the air. In high enough densities, though, it becomes visible as a bluish 'fog.' When it's in levels high enough to be visible in this way, inhaling it can be dangerous, and can lead to mana poisoning.

Liquid mana is the next most common. As mana fog becomes thicker, it starts to condense and collect in low points in the ground. Liquid mana is volatile, and off-gasses mana fog constantly as it evaporates (and usually condenses back down again once the fog levels are thick enough).

Solid mana occurs when liquid mana lingers for a long time. It forms a dense crystal, which becomes very stable. A person can pick up and handle most mana crystals without any fear of danger, and crystals are often purposefully grown to act as batteries for magitech devices. A mana crystal with a super-high density, however (such as Cendarii capacitors) has a risk of exploding if damaged. Standard mana crystals merely break apart into gasses and fragments.

Touching or handling mana on its own isn't typically dangerous. However, inhaling or consuming it in large quantities leads to mana poisoning. Symptoms include hallucinations, fatigue, a hard cough, muscle spasms, and a pins-and-needles feeling in one's extremities.

Continued exposure can lead to crystallization, where a person's tissue is gradually replaced with solid mana.

There is no cure for even mild cases of mana poisoning. Patients live with complications for the rest of their lives, and can experience flare-ups in symptoms when near active spell casting or in a zone with mana storms.