i like this old illustration of a wizard it looks like he's saying "I don't know! How the hell should i know?"

“I FINALLY get an apprentice to fall for the ‘Pull my finger’ bit and this happens?”

“You see the magical bullshit I have to deal with??”

Rincewind

This is what happens when an interviewer asks Alan Moore about the film adaptations

"Don't look at me! This here is some voodoo bullshit!"

This is his 'Fool of a Took' face

That's a man that hates doorways.

Merlin when he's sick of Arthur's shit

“It’s magic, it sorta just happens!”

What if that his actually his gesture for casting a spell? I’d say it probably works well.