@SamJaz: Sending the stone into the future is a bit trickier then just resetting it's position on the time axis. For that, he will need Accel End. The black sword appeared in his hand. He used it as a catalyst by sending mana through it and before long, the stone disappeared. He waited five seconds and the stone reappeared. Perfect. So he used the same technique from the stone jumping to send it twenty seconds into the past. And he didn't have to wait to get confirmation of his success as he suddenly 'remembered' the stone appearing not too long ago.