What if Powerball began with a Dash?
http://ddragon.leagueoflegends.com/cdn/6.24.1/img/spell/PowerBall.png
What if Rammus's Powerball began with a short skill-shot dash to activate? Rather than him just spinning on the spot like a silly sonic, what if he jumped forward a little to gain the initial momentum and could no longer sit still and spin. He would have to keep moving.
He would not be able to dash over walls, just a little jump forward.