Land and Magic
To use magic, what is necessary is a sequence in which a magus, once establishing contact with a magic foundation engraved in the world, sends a command to the magic foundation and executes a premade function. At this time, the fuel used for executing the function is magic energy, and the magus will have to send the command at the same time as the magic energy.
Magic foundations are magic theories that magus schools have engraved in the world, and magic is started up in accordance with those rules and systems. For example, the magic theory with the largest foundation is the “Teaching of the Lord” of the Church. Magic foundations engraved in the form of academia and religions fuse intimately with the veins of the land, and the magus using that magic foundation can perform magic anywhere in the world. However, if the magus leaves the land where his magic foundation was engraved in, he loses the backup of his land, and the force is certain to deteriorate.
Note that the case is different with magic foundations that are not academia or religions but rather are passed down through personal orally transmitted teachings, the limited inheritance in clans, etc. As long as the rules of those foundations are met, it is possible to exhibit the same basic effect no matter where one is in the world.