When Yuumi detaches from her ally as You and Me! (W) drops, she is left defenseless, so Soraka pokes from range with Starcall (Q) and overwhelms Yuumi's small heals with the large heals of Astral Infusion (W).

Sona's double-cast Hymn of Valor (Q) plus Power Chord (P) out-damages Soraka's poke, and Soraka's Astral Infusion (W) heals can't keep up with the area poke, leaving her pushed to low health.

Soraka is extremely squishy with no escape, so she is steadily chipped down by Milio's Ultra Mega Fire Kick (Q) poke and Fired Up! (P) burn. With the movement speed from Cozy Campfire (W), his allies shrug off Soraka's Starcall (Q) slow and can force all-ins.

Karma's Inner Flame (Q) poke out-ranges and out-bursts Soraka, and her Focused Resolve (W) root cuts off Soraka's poke windows, giving Karma the laning advantage.

Pyke's Death From Below (R) execute ignores healing and instantly finishes off low-health targets, fundamentally countering heal-focused Soraka.

Chained in Leona's Zenith Blade (E) - Shield of Daybreak (Q) - Solar Flare (R) CC, escape-less Soraka melts in an instant before her Astral Infusion (W) heals can even land.