Disillusionment was pretty awesome, and Mo stared at the blackboard over the professor's head as he considered the uses of the spell. Sneaking, for sure. It would be the perfect way to hide during hide and seek. What else?

Or wait... they were supposed to tell the professor what the charm was, hmm? Mo raised his hand eagerly and flashed a big grin at the professor. "It's like a camouflage spell, Professor. It doesn't really make you invisible, but it makes you blend in with your surroundings. It works best in shadowy light, rather than in straight daylight."