Stuff like magic needs to be very well watched.

I once was an admin for a star wars RP site where a dozen of us did a ton of different star wars RP with the same characters, but we organized all RP's in a timeline so in a sense it was one giant RP/adventure that lasted for about 3 years. All of our most memorable moments were when power levels are lower, the force wasn't something seen often and if it was then it was usually the enemy.

The second players started getting force sensitive the story kept moving, but the power level went through the roof and backtracking to a lower power level just made us feel robbed. So by the time our adventure was finished and we 'saved the galaxy' there wasn't much else to do, so our ice cream melted and we all eventually drifted off, some of the Guild and others simply stopping roleplaying period.

Stuff like that is something that really needs to be looked out for when magic enters, how much? Can you back track without bad effects? Will this cause a power rush that will melt the ice cream you worked so hard to create? There's a lot of charm in lower powered campaigns and roleplay's that a lot of people don't see value in until you've tried it yourself and overcame the challenges in other means, And once magic/the taste of greater power has been introduced, it's almost impossible to shake off.

TLDR: Caution. Brovo has some good guidelines if you decide to bring it in to begin with.
But before you even look at those ask if you even want to take the RP to such a power level, do you want results determined partially by a greater/mystical power that players can control directly? Is this something you think you can been controlled and stable, or something that will cause a forever power ramp?