My problem with new Sona's heal thingy, though?
Aura gives a shield. Shields prevent damage. Heal bolts do %missing hp as bonus healing, which means you have to have taken damage. Short of deliberately letting some damage get through, one part or the other is going to be less than ideal. Unless you're helping someone who's trying to flee from a fight, in which case, sure, the %missing hp and the shield both help increase survivability, but in that case, thanks to the auras relatively small radius, you have to follow them unless you're either proactively watching for the first person to have to bail out, or you shielded them on their way out of the fight by accident. You can't really pre-buff with a shield without pissing away a good bit of mana on wasted healing that isn't doing any good, besides maybe triggering your Ardent Censor. Admittedly the cooldown is low enough that your shield-granting abilities will be back up by the time they're needed, it still feels rather inefficient.
Then again, that DOES mean there are two ways to use the heal without being punished for slipping up a little. Want to shield before they take damage, but was just a smidgen too far away and they got hurt before you could get to them? Well, the shield is on them, albeit later than expected, and odds are the heal bolt just topped off whatever damage they took. Running from a fight and your buddy is ignited and about to die? Heal, regardless of the reduction, and slap a shield on them as well to pad out some of the ignite ticks. Win-win, provided you can manage your auras well enough.