Soraka W

Soraka W, Astral infusion alredy costs hp but why does it also cost mana? I know that the max hp and low mana cost price cost is just for the extremely low cooldown it has. Am I right? When im playing soraka and i alredy use all of my mana ( healing everyone damaging the enemies.), when im about to receive a ally jungler gank but i have no mana so i cant use my heal, so soraka is completly useless when she has no mana. When i first use her W didnt notice it uses mana cause i thought " if it alredy costs me 10% of my maximum hp it shouldnt use mana, cause the hp sacrafice was alredy a high price to pay. When both bot lanes are fighting early game soraka w has about 3.5 sec cooldown and it's power is about 200hp healed so when she uses it the first time to heal the adc and it is losing hp really fast it isnt that affective cause in 4 sec the adc is nearly death so here is my new W:

Astral Infusion Cooldown: 4 sec/3.5sec/3sec/2.5sec/2sec New Cooldown 2.5sec/2.375sec/2.25sec/2.125sec/2sec While healing a friendly unit on combat.
The Cooldown is Increased to 6sec/5.25sec/4.5sec/3.75secsec/3.0sec while the friendly unit healed is out of the combat. Cost: 5%/7.5%/10%/12.5% Max Health, 5/10/15/20/35 Mana Range: 550 Soraka sacrifices a portion of her own Health to heal another friendly unit. Passively heals Soraka when she lands Starcall on an enemy Champion. Passive: Each enemy Champion hit by Starcall (her Q) heals Soraka for 25/35/45/55/65 (+40% Ability Power) to 50/70/90/110/130 (+80% Ability Power), increasing based on how much Health Soraka is missing. Active: Restores 120/150/180/210/240 (+60% Ability Power) Health to her target ally. Cannot be cast if Soraka is below 5% Health.

Voting optinions:

Below are my questions for you to answer. ( Only if u want) Vote 1 : I like your new W cause Soraka early game is now better and she has a higher % to win the game. Vote 2 : I prefer the old W cause Soraka is alredy a lit bit op and with this on combat buff she will be a monster. Vote 3 : If Soraka get this update the solution to destroy it is pretty easy: Focus her first and all heals are gone ;) .