You get the ability to perform one level 1 spell from an RPG system of your choosing in real life. The RPG system must already exist; you can't come up with it on the spot. You can cast the spell as often as a level 1 mage/wizard/ in that system. If your system of choice does not have levels or classes, pick a spell that a novice magic user can use. You will be able to use it as often as a novice magic user.
What do you choose? Explain your motivation.
Old school Wish.
Now let's see if the DM is merciful, an exactly as written rules lawyer, or a dick.
>level 1 mage/wizard
>wish
Enlarge Person.
I use it for porn.
This man can't read.
If it's level 1, I go with Cure Light Wounds.
Praise Jesus.
Prestidigitation from Pathfinder.
Because it cannot duplicate any other spell, and there are no other spells, I can do anything with it.
No, I kid. It's just a supremely useful, harmless, infinitely reusable spell that can do enough things that it would never be not-useful in many situations.
Would you start your own religion?
Grease, for the comedy potential. Or maybe Ghost Sound so I can create the sound of crickets whenever there's an awkward silence.
oWoD Mage, Mind 1
Because it's literally no contest. I don't think there's any RPG that has a more powerful effect for a novice magic user than Mage, and between Entropy and Mind, I think Mind allows you to more spectacularly succeed in modern society.