The Practical Laws of Magic
Of course, people attempt to circumvent these laws. It's simply human nature. But the declaration provides the respective governments of Aren a legal pretext for addressing such transgressions.
The Stoltgard Concord also conferred upon the respective nations of Kumlar, Khune and Khadid the right to enforce these laws a they see fit. In Kumlar, the College of mages is responsible for the investigation of magical issues and for the execution of justice.
Control Your Emotions
Magic is colored by your emotion. Lose control of your emotions and you may lose control of your magic.
Seek Not to Command Another
Subverting Free Will is a road to conflict and rife with the taste of forbidden fruit… And often it comes with unforeseen consequences.
Seek Not to Alter the Flow of Time
Paradox is a vicious Bitch, and you will suffer for it.
Seek Not to Draw From the Underworld
The Underworld is Lita's domain, and taking someone from the Underworld has serious real-world consequences. Nobody wants undead around. Necromancers don't tend to last very long in this world.
Seek Not Beyond the Sphere of Ena
Ena is the Primordial God, the creator of all. What lies beyond is unknown. Breaching the sphere of reality threatens to let in whatever is outside and perhaps weaken the surface tension that keeps this reality consistent. The College of Magic lobbied hard for this addition to the Stoltgard Concord, but to date, no-one is aware of any attempt to go beyond the bounds of known reality.