Okay Sona is one of the least appreciated champions I find which sucks because she is very effective and easy to play decently. This is the easy build and of course changes in game if facing an AD team get legion first and other adjustments as you see fit. Comments are appreciated and will be considered for my own development as well as others who one day may be keeping you jamming in lane with some beautiful music.

One thing all Sonas (or supports in general) must understand is taking last hits on minions during lanning defeats your purpose as now the carry must not only carry but also is losing gold. Instead ***ult the opponent in lane with white damage as you won't hit hard no one will really pay attention to you till they are all ready at about 75 percent and then your carry can keep them from XP. If you are saying but what about my gold more gold means more support faster. Well lets talk numbers. if you are lanning against a team that is identical to yours their support takes no last hits and carry take them all and for sake of argument you take 1000g as support in lane then when your opponents have a BF sword or Needlessly Large Needle your carry is only just now touching lvl 1 boots. that is a huge disadvantage which will lead your lane to dropping or your carry from bursting during the gank.

With all of Sonas auras her simply standing there gives an advantage to your teams in a team fight why not capitalize on that so to mitigate damage even more that is why as oppose to huge heals and increased damage I build auras. building AP, though can be useful and in games where damage is lacking I will do, makes you only help one person at a time as auras do not stack with AP. but building auras help the team when your opponents don't single target someone you can get an easy win. one thing to be aware of though if you are planning a gank keep range you don't want your opponents to see the aura and know your there.

My rune choice is based highly on the fact that I hate having to pick up mana pots or worst leave lane. (when support leaves lane the carries who previously were cocky with all these fun buffs die) the cool down reduction is for the decrease on the GCD applied when you switch auras so you can keep more then one up for a bit (very nice when running away from ppl switching between song of celebrity and aura of perseverance so you get health and speed. I end up slightly over cap which is fine because I get to cap much earlier then most champs.

Masteries are pretty simple to understand I use flash and CV for the assistance to team and self flash in with a crescendo and CV baron uses to those 2 masteries as support never end. And of course flash over a wall to your waiting team when the opposition comes chasing the cute weak bait that is Sona. I can't think of any event where I would want anything besides these summoner spells but the only one almost worth getting is ghost for the added escape option but the CV more then compensates for that by illuminating the better escape option. nothing is worst then escape the 2 that are chasing you just to end up in the grasp of 3 that are waiting for you its terrible. (thanks to runes I don't usually have mana problems once i get my stone so clarity is not needed.)

Pros
-very dynamic with heals and speed
-can do damage with HoV (a lot early game if tied to 3 stacks)
-easy to play without need to target on basic abilities
-if you time your 3 stacks correctly you can slow a chaser then build them up to drop damage output of that fiddle as he ults in by 20 percent.
-Your ult is a great way to stop damage on a team right after initiation of a team fight.
Cons
-Fragile to ganks so keep your back safe
-Will have mana problems early if your lanner is crazy
-Heal is weak till level 5ish