An idea to bring Ashe back:
Debuff: Slippery Ice. Enemies who are effected by slippery ice and attempt to use a dash get stunned for 0.75s.
Ashe's W now creates an icy field on the ground for 2 / 2 / 3 / 3 /4 seconds, enemies who stand on it get debuffed by "Slippery Ice". This effect is renewed every second for enemies standing on the frozen terrain.