Change Soraka's W into Rejuvenation (no longer Astral Infusion) and no longer cost health only mana. It only regenerates health no longer burst heal like Astral Infusion. When you hit an enemy with your Startcall, you get the Rejuvenation buff and when you cast your W to your ally while you're under affect of Rejuvenation, it doubles the heal regeneration and the Rejuvenation duration is extended for 5 more seconds on ally (s).
Add: Soraka's Equinox should have slow effect for more Mobility and Survivability. With all this assassins and divers diving at you, Starcall slow and move-speed buff is not enough survivability. It should also can stun minions and/or large monster including Tibbers, Daisy, Voidlings etc. for peeling them off off your adc (if needed) and for defending your base and turrets. It should also proc your Rejuvenation when you hit a large monster with you Starcall including Drake, Rift Herald and Baron.
I found this thread, its about Soraka's Equinox: https://boards.na.leagueoflegends.com/en/c/gameplay-balance/Zp51l4KX-petition-n-1-about-soraka-qol-buff-to-es-refresh-rate