I want to be clear that I main Sona and this guide is more for my own benefit than the benefit of anyone else. Secondly, I am Bronze I and I may be way off on all of this. I am 45/55 in wins with Sona so I feel like this works but it may just be for my elo. Any comments of advice I will appreciate greatly and any derpyderp nerds that don't like what I have to say please don't leave anything at all. Finally, there is very limited amounts of information about Sona as a seriously competitive champion online. Which is the second reason I felt compelled to draft this guide.

Ardent Censer is a prefect synergy item with your W (heal). In lane it provides your ADC more DPS while protecting him and gaining value in exchanges. But more importantly is the differential in damage when Diminueendo is active. You will diminish the opposing ADC's output by 20&(+undefined scaling amount of AP) while healing your ADC which procs Ardent Censer, Increasing the Damage per Second that your ADC is producing. Additionally you provide a shield when you are near enough to your ADC (which also procs Ardent Censer). This is the kind of exchange you want to capitalize on as much as possible.

Iceborn Gauntlet provides a much needed boost of damage on your Hymn of Valor, while before Sona could chunk enemy champions easily, you must rely on the sheen proc as well as your passive to carry the damage based on AD as opposed to AP. Which is why I build tear into Muramana now. Also the Iceborn Gauntlet abilities will allow you to flee in less favorable situations. Iceborns slow, with ardent censers movement speed bonus along with your kits movement speed/slow(from Song of celerity/Tempo) as well as exhaust and your Frost Queens Claim ability should allow you to kite or flee whitout having to burn your ult or flash. Of course sometime you need that little bit more and you can use your ult or flash to reach certain safety.

My point being that this item build turns a champion with no true escape mechanic into an impossible to catch utility machine. Sona traditionally is a champ that excelled in exchanges of damage is not played more like a thresh who wants to make the plays instead of carrying damage. This is my point of view anyway.

Flash Exhaust. Nothing else. STOP! Don't do it.