Rengar Ult balancing

I think Rengar's kit is perfect, albeit unbalanced, but a few minor tweaks could help prevent massive snowballing that is typically seen when someone is doing decent as him. Firstly, a slight change to how his ultimate warning works: **His ultimate warning should scale with his **movement speed . This is more of a quality of life change to prevent him from assassinating whomever he wants with relative ease. It would make his positioning much more important, instead of 'press R, run forward, kill them and win'. With this change it could give the opposing team a little extra reaction time. I think this is needed because as of right now, a Rengar with Tier 2 boots (Excluding Mobi and Swifty boots), a Yomuu's, and a Statikk Shiv can land him at a nice pace of about 475 movement speed. Now with that movement speed combined with his ultimate speed boost of an extra 15%, coupled with all three cloud drakes, that gives him roughly 585 movement speed. This gives his target almost less than a second to react, and if he is fed in even the slightest way, that is almost a guaranteed kill. This minor tweak wouldn't be a a hard nerf to him, more of a built in counter that is already there. I wouldn't suggest making the radius much larger on the warning but rather for it to scale according to his movespeed an a small scale. This would prevent major snowballing and make Rengar more challenging to master but also more fun to play.

TL;DR: Rengar ult warning (!) scales with his movement speed on a small scale to prevent major snowballing

Any thought or additions would be welcomed!