Mana

In Zemia, all magic is fuelled by Mana, which is a substance can be thought of like dark matter (or Dust, if you're familiar with His Dark Materials). It is a gas-like substance that is normally invisible and able to pass through solid matter without any interaction.
Any being with a soul is able to influence the flow of the natural currents of Mana, and by concentrating enough of it in a single spot they can have a tangible impact on the world - this is the basis for all spellcasting in Zemia.
An individual's ability to manipulate Mana is dependent on their mental and physical 'power'. This is dependent on a factors like their willpower and mental state. This is why spellcasters, when shocked or scared, may find themselves temporarily unable to cast high-level magic.

Magentium

See article: Magentium
Magentium is a substance originating from the Purple Mountain, Şūfmibū. It holds the unique property of being the only nonliving substance able to interact with Mana. This means that it is used in every magical object, including vials for magical potions. It can also be formed into spell-beads which can store Mana within and then release it to give their user a brief boost to their magical capabilities.

Spells

The exact way that magic must be manipulated to cause certain spell effect can be very finnicky and complicated. Extensive study of spellcasting, a.k.a. Wizardry, is a lifelong pursuit. All spells are a series of complicated mental steps ordered in a specific way, analogous to a programmer writing lines of code. This also means that, as the framework and understanding of spellsculpting evolves, older spells can sometimes be 'rewritten' to be more powerful, or more efficient.

Spell Levels

Spells are generally grouped into arbitrary 'levels' (sometimes called 'tiers') depending on how much mana they require, which roughly translates to the potency of the spell. These levels are useful for legislation as they allow governments to restrict the use of certain levels of spells, and the highest level spell that a person in able to cast is a good general indicator of their magical proficiency.
It is generally known that the most powerful of mages can reach spells of around 10^th tier, although certain beings - like the gods of The Pantheon - are rumored to have 11^th tier spells.
The weakest spells are easily cast by any living being with very little strain, hardly more effort than just waving their hand. These are labelled tier 0 spells.
An example of this is the Fireball spell, which used to be considered 4^th tier until a particularly clever wizard managed to rework it to be more mana efficient, decreasing it to 3^rd tier while still retaining it's power. Tier is defined solely by the mana cost, which does lead to discrepencies in the 'power' of spells in the same tier.

Type

Metaphysical, Arcane