Schutz Fields

Without a magic shield protecting a town or city, so many would not see the morning. It is a broken world that we have inherited and we must be ever mindful of that. We must see to it that proper care and preparation is overseen every day even if few appreciate the work.

— Jun'ichi Takenaka, Shield Warden

Overview

The wandering and unpredictable Wild Magic Fragments necessitates the use of magic shields, usually powered by Schutz Crystal, to protect a settlement from destruction. These crystals give this field the name Schutz Field. Otherwise, a sudden magic field or worse could become a mortal danger and prevent the establishment of any kind of large settlement. These kinds of magic shields primarily protect against the formation or passage of wild magic fragments and not against natural forces like rain or fog. This is by intention as such a shield would prevent the passage of people into and out of the city.
Schutz Fields can also be produced by sailing ships, usually the larger kind, in order to provide some measure of safety from wild magic.

Military Defense

However, Schutz Crystals can be powered even more to protect against all manner of matter and energy in defense of the city. The Shield Custodian can charge the crystals for limited periods of time to produce a truly great and powerful Schutz Field. The shield in this state is strong enough to defend the settlement against a siege. However, this overpowered state of the shield can only be held for a limited period of time depending on the strength of the custodian(s) and whether the settlement has more than one.

Shield Custodian

The Shield Custodian is responsible for the operation, maintenance, and protection of the Schutz Crystals that power the settlement's magic shield. It is a station of great responsibility that is not usually noticed by a settlement's citizenry. The custodian must be a trained magic user able to charge the crystals with mana on a regular basis.

Note(s) from the Archivists:

Does anyone know who the Shield Custodian of Centrum is? - Archivist Enna 
I think the city has three custodians. They're triplets, I believe, of the reclusive Nightwinds nobility. - Archivist Rena