1246 movement speed.
See, I know speeds FAR greater than this have been achieved in controlled environments (Thank you Vandiril). But, this was just in a normal ranked game, a rank 5 powerball, and a 
Righteous Glory active. Only 
Ninja Tabi as boots, no MS runes in his build, and only maybe 1 or 2 MS masteries.
And, its possible that he could have been able to reach a speed MUCH faster than that. He did hit me near the end of his powerball, but he still had enough left to probably reach 1300 movement speed.
Why am I showing this to you? Meh, just cause I thought it was hilarious that he could reach this speed without even trying.
Ok.
