Okay, either her Gargoyle was being lazy or she just hadn't got the spell quite right... Derry scowled at the little statue and poked it with her finger, "Come on, Gollum." she said, then waved her wand at it again. "Piertotum Locomotor."

OH HEY! LOOK! IT STRETCHED! Hmmm... "Run." she told it firmly, and the little fella set off around her desk... but he wasn't running, just walking... maybe she really needed to get the spell to be stronger. "Stop..." she told the gargoyle with a little sigh.

"Come on, we'll do it properly this time, Gollum. Piertotum Locomotor." She watched Gollum stretch his legs out and waited for a second before saying "Run."
...
Oh! He did it!! He was running! Derry's eyes lit up as she watched the stone creature run around her desk. "Back flip." she told it, and it did! Except it stumbled upon landing... maybe they should keep trying...