Once again it looks like Hi Rez has taken a sledgehammer to a problem that needed a scalpel. Not only did they slow down Imani's frost bomb but they also changed the card that increased the root to a card that increases its speed. So now it's a slow moving ball with a root that can't be increases on a 20 second cool down that isn't affected by chronos. Absolutely ridiculous.
I'd be fine with the nerf to speed AND root time but to balance it out, the cooldown should be reduced. A 20 second cooldown for what it does now is waaaay too long.