The main resource of the Mages in Thistleland is their magic.
Mage Magic is in principal based on information put into physical form, and is extremely similar to Southern Magic in operation. The principal difference between the two types of magic is the Mage Magic projects it's effects externally from the object the spell is inscribed from, where Southern Magic operates specifically on the item that the spell is inscribed on.
While the magic Mages use is highly varied in implementation, the essence of the magic is in linking information that can affect reality to a physical form. Typically this is done by inscribing the spell onto a scroll, which when read acts like a magical form of programming reality.
Mages will often use parts of the spell's programming to tie activating the spell to a gesture for quicker use or inscribe the spell onto an object to enchant it, effectively making the use of said object activate the spell attached to it.
Sometimes, an advanced made will use other ways to create and activate spells such as layouts of gardens or buildings being carefully arranged to represent the data for a small spell. Some of the most powerful Mages in Thistleland are known to be able to recite spells directly from memory, visualising and recounting the spell within their mind wholly to cast the spell, and possibly even create new, tailor made spells with little more then their thoughts.