PBE Sona
Sucks. Scroll down to Sona.
Tldr: Auras ranged got buffed from 300->400 No longer increases duration of aura by 2 if it tags an ally Q damaged lowered at later ranks, cooldown increased at earlier ranks W has a slightly better base heal and shield, removed the percent missing hp E no longer gives ms to Sona, and instead gives a range buff for a few seconds R no longer empowers Power Chord's effects but now decreases base cooldown of abilities.
What the changes mean: Sona's levels 1-3 are basically unchanged. With the change to the E, Sona now can't speed herself up to reposition or to get away from enemy champions. Instead, she gets a range buff, which is nice if you want to poke someone down, but becomes utterly useless in any other situation. The base cooldowns getting lowered with each ult rank sounds nice, but now Sona's power chords are nothing late game and she becomes a spambot that NEEDS to build mana regen (even more so than she does now).
The E change absolutely sucks because Sona was already immobile and squishy. Now she's even more immobile. Great. Speeding yourself to reposition in teamfights and get good ults off felt great. Now E gives ms to her allies but no ms to Sona. That makes so much sense.
I hope to God that the E change gets reverted because that is literally the worst change to a champ I've seen in ages (and yes, I'm counting the Morde rework).