by Phoenix in the Ashes » Thursday 6 March 2008 7:53:19am
Just to make something clear, this isn't the exact same type of Time-Turner that Hermione used in PoA. For the purposes of this RPG, the Time-Turner that she had was not one of the stronger ones. The one she used worked very simply, simply taking back time one hour with every flip of the hourglass-shaped pendant.
In my opinion, that would not be the extent of magical powers in respect to time. They would not give their most powerful store of time-turners to a thirteen year old witch, after all.
What I'm getting at here is that the one John found is one of the most powerful, perhaps the most powerful time-turner in existence. You'll notice that the scenario is set close enough to the time when all the time-turners at the Ministry were destroyed? That was for a reason. Maybe someone knew that that was going to happen, and hid the time-turner to keep it safe.
The main point I'm trying to make is that we don't know the limits of this thing's power. It's almost certain that it's time travelling properties don't match that of the Hermione's time-turner, as John only went back half an hour.
If you noticed, at the time John was fingering the pendant he was also very much wishing that he had not been so stupid on his bike. One could say... that he was wishing he could go back in time to stop it, though of course not literally, as that's impossible, right?