if this is the one im thinking of, it's a mega repost, but is one of the best things ever. on my phone so I can't tell. I cast magic missle on the darkness!
can I do them?
No no, not that. He goes "Now it's fine for the final battle" then lights a sparkler. As it shoots of sparks he keeps going "Magic missile!" and when it stops he whines and goes "oooh I'm out of mana!"