The Secret Triwizard Challenge

You shout, "Incarcerous!" Ropes shoot from your wand and envelop the spider's front legs, including the stunned one. The spider attempts to move toward you, but trips. It begins to gnaw at its bindings, but the process is hindered because it can't position its stunned leg well. You need to move quickly.
You sprint around the spider, which tries to lunge at you, but it falls on its face again. You hear a snap as you exit the clearing, thankful you made it through before the spider bit through the ropes. But you can't waste any time being thankful - you have a race to win!