flaw name-practical joker
effect-every adventure you must make a intelligence roll or do a annoying or dangerous practical joke on someone in the party
not sure what a points you would gain from this flaw
question-what sort of practical jokes could wizards do with magic?
Spell: Tickling Touch (lvl 4)
R: Sight D: Mom T: Ind
Creates the feeling of someone tickling a part of the body of the target. It could be a quick tap, a rubbing... 
. Ideal to be cast without voice & gestures, and if you are a bit specialized in Imagonem (a prankster should be), then you could affect even mages... With a bit of imagination, you could even create the feeling of little legs crawling under your clothes, or between your hair...
(Base 1, +3 Sight)
What arts? I don't see any written.
That is CrIm. Base 1 affects 1 sense (touch, in this case)
Cheers,
Xavi
Yeah, sorry it´s Creo Imagonem, i forgot . Here´s another one:
The Undomitable Chair
Rego Herbam 10
R: Sight D:Mom T:Ind
Makes an object made of wood to shake uncontrollably for a few moments. It can be used to disarm someone, but the original purpose was to make a VIP feel dumb . Uses of the Unseen Arm (Re Te 5, with Herbam requisites) for fun with a chair is also recomendable.
(Base 3, +3 Sight)
Edit: Wrong with Technique
Here´s another one:
A lot of Good Omens
Rego Corpus 10
R: Sight D:Diam T:Ind
Makes the target unable to control himself and start sneezing almost continously for the duration. The name of the spell came from the extended custom to think that sneezing is a powerful omen. A cruel Magus could change duration to Day .
(Base 2 (Make the target lose the control of a body part), +3 Sight, +1 Diam)
What do you fine people think the flaw is worth?
Isn't this covered by personality traits anyway? It's not necessary as a flaw.
I think that it would be a Personality Flaw. There isn´t anyone in the RAW, but we could use Compulsion Flaw (pranks), for example. Note that this compulsion (or another personality flaw) doesn´t distinguish between PC and NPC, so your character could try to prank anothe magus companion, the bartender, or a lonely warrior... Although i suppose he wouldn´t try to prank the local bishop, or the archmagus, at least not for a Minor Flaw .
Any new magical practical jokes out there?
BUMPATY-BUMP-BUMP
bump
Hi, Abe! If you think about it, practical jokers like to poke the powerful, as a rule. In Ars Magica, that would be your fellow wizards, all of whom have Magic Resistance. He would want "sleight of hand", so he could do things without magic, while making them look like he did magic, so as to get them coming and going. "How did you penetrate my Parma so easily?!?" (I'll be weeks getting the red out of my Beard!).
would "slight of hand"be a skill or a talent though?
Legerdemain with a focus in slight of hand?