Mana

Mana is used for casting spells and other magical activity. Mages have a mana core for storing mana. The amount of mana a mage can store and the rate at which it regenerates depends on their magical prowess.
Some people develop this core naturally, others need to have it nurtured. Around one in twenty students at Tyrness Academy have a natural mana core. Generally, magic manifests around the onset of puberty.
Mana can be coalesced into a liquid, the smallest unit of which is called a drop. Any mage can coalesce mana, and it's used in enchanting, alchemy, and many other forms of crafting. Liquid mana is highly unstable and will evaporate quickly or even explode at a sharp impact. The explosion is not violent, except in excessive quantities of over a hundred drops, but it can light fires and cause other problems.