How to make Sion's E (Roar of the Slayer) to be more impactful and still balanced

ACTIVE: Sion bellows in the target direction, dealing magic damage to the first enemy hit, knocking them up for 0.25 seconds and then slowing and crippling them for 2.25 seconds.

If the target is a Minion, non-epic Monster or a if a champion dies to the ability, it is knocked back, in the same line, up to 1300 units away from Sion, dealing the same damage and applying the same effects to all enemies it passes through. Projectile minions and monsters take their damage once they are stopped, by either colliding with terrain or reaching the end of their trajectory.

Magic Damage: 50/75/100/125/150 (80% AP) Slow: 40/45/50/55/60% Cripple: 20/25/30/35/40%