Magica Density is an interesting phenomena. Normally it does not matter much, as Magica is everywhere and endlessly replenishes.

However, as all Magica users know, it is more of a stream than an ocean. So people use wands, charms, and various items to store up and allow for a greater amount to be used at once. Demons carry around vast reserves of Magica inside themselves, converted to Demonic Energy. Many monsters also contain some amount as well.

But the ambient amount DOES change. Some areas, especially the very edges of the Continent, are quite low. The Interior and the New Land have the highest naturally occurring amount.

This increase allows, over time, for Monsters to grow far beyond what the size they could normally attain. Demons as well seem to thrive in such environments, as from all reports the Demonic Planes are fairly low in natural ambient magica.

The Grand School of Magica is of course built on a kind of Magica leyline, to benefit the students.

Interestingly the Snow Queen's Domain has showed a surge in ambient magica, although it seems to have been subtly altered. More research will have to be done.

If we could add, or deprive, an area of Magica it could be VERY useful as a tool for combatting monsters and perhaps even Demonic incursions.

-Advanced Magica research and development course at the Grand School of Magica