The focus, is represented in different way, by different thing, depending the enviorment in wich the spell is going to be Cast.

The SpellBook and Reagents.
Different mixtures of reagents are used to build speciall focus. Each mixture must be carefully replicated as any mistake could lead to a terrible accident. Every step, that the Caster should take to mixture this reagents is written in his book, the SpellBook.

Mages can learn the spells that they need and transcribed them into his book, or buy the spell from another mage.

The Magic Scrolls.
The magic scrolls, are no more than "freezed" spells, ready to work. Blocked by a sealing, this scolls include the necesarry mind and eheter energy to function.

BlackRock Stones and Runes.
First discovered and used in the Stygian Abyss by sir Calbirus, BlackRock is a rare element that can easily manage the flux of the Ether energy.

Shaped as Runes, representing each word of magic, BlackRock Runes are the easiest and quicker way to cast a spell. Different from the reagents and scrolls, BlackRock runes can ber used as many times as the mind power of the Mage can resist. The making of a BlackRock rune is a very long and hard process, making this runes to be very rare.