I know you will soon change Kayle for the worse. This is because, currently, Kayle is both popular and strong. I realize this is going to happen, and only ask that you do not do so haphazardly. As such, I ask you only nerf Kayle's ratios, and do not change the cooldown or duration of any of Kayle's spells.
Kayle's popularity is, of course, caused by the Season 3 changes, which cast out many of her weak matchups and elevated her strong matchups (and buffed her AP itemization). It would be silly to substantially nerf Kayle because of what is currently FOTM.