A few things to remember about worlds with magic:
1) Even level magic users are higher threats than a nonmagic user
2) If someone can do magic you need to know what kind if you want to continue breathing in a way that is not detrimental
3) When going up against an Archmage consider combat a last resort, your first option is to usually run away and hope they don't do something to prevent that, even if you have an army to your back.
Archmages are known for their ability to change the tide of entire battlefields, not just the area they are immediately in, and some are known to have power that extends beyond the boundaries of major cities and some small nations.
