From the wiki:
No summoning is allowed in Syliras, especially within Stormhold Citadel. If something unsavory is summoned, it tends to eat the summoner and anyone nearby, leaving a mess for the Knights to clean up.
Anyone practicing dangerous magic such as Fire Reimancy or Alchemy will be held responsible for any damage done to people or property within they city.
The bottom line is that the knights are likely to come down hard on any major public display of magic that disturbs the peace. My PC is a reimancer but I would only perform magic in public within the city in an emergency... in private, or outside the walls, is another matter of course