Soraka's Heals should heal over time scaling with the cd of W

Soraka's W being flat heal is really oppressive in the lane phase considering how easy it is for her to heal her adc for 250 while consuming 10% of her HP( at lvl 8 her HP is around 1100). what i was thinking is her W should heal over time scaling with the cd of her W, so lvl 1 she heals for 70~ over 4 seconds and at lvl 5 she heals for 250+ over 2 seconds, with 45% cdr, she'll heal for 250+ over 1.1 seconds. soraka will stay broken( lacking counterplay ) because she can stay behind the adc and heal him constantly to ensure his survival.