The Secret Triwizard Challenge

You cast Duro. Whatever was making the ground sticky is now stone, and you continue forward. You're in the middle of the clearing when something huge blocks out the light of the moon and falls directly on top of you, almost crushing you. Instead of staying on top of you, however, it falls to the side. You scramble away from it and finally get far enough away from the huge thing only to see what it is - a GIANT SPIDER.
Its feet are used to walking on the sticky ground and can't quite grip the stone. That doesn't stop it from glaring at you, red, beady eyes full of hunger. It's blocking the clearing exit and about to charge.
What do you do?