Hi, I'm DJ Tiger and I am currently plat 2, top 3% of ladder with a 56% win rate solo Q and 60% win rate on Sona. This is my build believe it or not and it has been working extremely well for me. The strong point of this build is obviously ardent, Sona having a skill on her kit giving your whole team a shield every 4-5 seconds makes her the most powerful champion to build ardent with. The key to winning games with this build is learn how to make smart, thoughtful calls and force your team to group for early barons and avg 25-30min wins. Every time you use Q or W it is very important to move around to make sure your whole team gets the aura, ardent giving a lot of attack speed and on hit damage is crucial for pushes and objectives and transform a push that usually gives you a t3 turret after a team kill into a push that will straight up end the game before they get to re-spawn if you have baron buff.
That's pretty much it, with some practice you will get some freelo using this, and also if you're wondering about the Dead's man Plate, you just use it as a stat stick and the crazy movement speed buff :). Enjoy.

P.S. If you think I didn't put much effort into this guide you are right. I put as much effort in this guide as I put in my ranked games to get plat 2. MegaLUL