Soraka vs Swain

Hit a champion with Starcall (Q) before Astral Infusion (W): Rejuvenation heals you, lowers the heal's health cost and passes to the healed ally.

Get to your wounded allies quickly: Salvation (passive) makes you run faster toward them.

Place Equinox (E) under an enemy who is channeling: the zone silences them, then roots champions still inside at the end.

Save Wish (R) to rescue an ally anywhere on the map: the heal is stronger on allies below 40% health.

Get out of the Nevermove (E) path as it comes back: it only roots on its return to Swain, then he can pull each rooted champion to him.

Leave the area as soon as Vision of Empire (W) appears: it strikes and slows 1.5 seconds later, and each champion hit gives him a Soul Fragment.

During Demonic Ascension (R), back off and hit from range if you can: he only drains nearby enemies, and his form ends when he stops draining.

If you have Grievous Wounds, apply it during Demonic Ascension (R): the drain heals him every second, and that healing keeps him alive.