It's an obstacle course. No, it's THE obstacle course. Flaming hoops! Spinning blades! Crushers! Spikes! Catapults! If it's deadly, it's here. Well, there's no deadly animals or anything like that. Rainbow told you she wanted a manticore in there somehow, but couldn't figure out how to get one in it. She's still pretty sure that this is the most dangerous, most deadly and most coolest stunt course ever devised, and who are you to doubt her? And now she's going for a test run before she shows it off to everypony tomorrow. Why? Because awesome ponies do awesome things, and this was the very definition of the word.