This is my first guide, so I will appreciate any and all feedback. If you do down-vote my build, please leave me a comment, I actually like the criticism as I feel it makes me a better player.
Pros and Cons
* Top notch support capabilities
* Has infinite duration team buffs
(as long as skill is kept on)
* Has Buffs for all situations; attack, defense, speed
* Very short cool down heal
* Ultimate disables all who are hit while having a substantial range
* Excellent mana efficiency
* Limited damage capability
* Extremely limited escaping mechanisms if ganked or focused
* Healing target is lowest heath ally (cannot just heal who is being targeted)
Countering the cons
* For Sona's damage capabilities, she is primarily support, and thus will not have the same damage output as a carry. Later in the game her passive does give you a decent boost as you will be constantly changing aura.
* Three of my build items add ability power which will increase your damage, reasoning will be stated below. As for her lack of survivability, this build will net you a fairly hefty health pool. Zhonya's Ring can also be substituted for a defensive item if needed.
* Preventing ganks through map awareness and positioning in team fights will be key for getting around her limited escaping mechanisms. I also take ghost and flash for my summoner spells for those unavoidable situations if needed.
* Sona's heal while being the lowest health traget, you can control it to a certain extent through positioning. I try to be closest to the person I wish to heal, and if possible have that person between any other allies in the area.
1) Start with the Meki Pendent and a health potion. The pendent paired with Sona's awesome mana efficiency, you will never have issues, and her heal will be more than enough to keep you and your lane partner topped off. Potion is just for a little bit extra at the start.
2) Stay in lane until you can afford Boots of Swiftness. Sorcerer's Shoes just aren't needed, you are not there for your damage and the extra speed from Boots of Swiftness allows for more flexibility with your positioning. If you are facing a heavy debuff/cc team, you should most certain buy Mercury's Treads instead.
*****If you are confident in your ability, purchase a Mejai's Soulstealer at this point, but you have to be able to maintain 20 stacks*****
3) Next, you should purchase the new item, Kindlegem, apologies for it not in the build, I will add it when its in the system. This will then be upgraded to the other new item, Shurelya's Reverie. This starts you on the path of maxing out your cool down reduction, a must for Sona.
4) The Archangel's Staff is next, this will improve both your damage and healing, and allow you to start building a sizable mana pool. You will be casting spells constantly, so it's far easier to cap the passive 1000 mana bonus than on most other champions.
*****If you purchased Mejai's Soulstealer earlier, do not purchase Deathfire Grasp, you will get one or the other*****
5) Next you should grab either the Innervating Locket or the Deathfire Grasp. One gives you some more ability power and the other more regen, health, and mana. Both give more cool down reduction. Get the second one after you make one.
6) At this point you quite honestly cannot run out of mana, and your cool down reduction will be more or less capped, 39%. If you are doing well, grab Zhonya's Ring for some more ability power, or if you find you are getting focused too much in team fights, pick up some armor or magic resist depending on you opponents strongest damage dealer.
Masteries and Runes
For masteries I use a fairly standard caster/support build, pretty self explanatory.
Runes are about the same here too, standard caster build. I do urge the flat health quints however, the increase in survivability at the start of the game is too good to give up. Some like to go all AP/level for runes, and I can see this working, and I feel like changing marks and/or seals would be fine, but I again strongly urge you to keep flat health quints.
Skills and Skill Order
Passive: Power Chord
This gives your basic attack a little extra punch after you cast 3 spells and lets your aura stay on for 3 seconds after you switch. Basically, this gives you a little bit of harassing power early game and allows you to have all aura on once you cap cool down reduction.
Q: Hymn of Valor
I max this first. This gives a small AP and AD boost to you and those around you, as well as when activated, fires a projectile. If there is a champion nearby, it will almost always hit them instead of a minion. Many other guides are saying max this last, but I disagree. The AP and AD bonus caps at +20, which certainly helps, but is not much end game. It is however a fairly large boost for your lane partner early levels. It also gives you a very nice harass tool since the damage is very good early game if you level it. Leveling this first is NOT so you can do uber damage, it is to buff your lane partner (since this is when the aura stat boost is most effective) and to harass (not to last hit either, your partner needs the money more than you do).
W: Aria of Perseverance
This is your heal on activate and gives you armor and magic resist from the aura. I one point for it at level 2 and then max it second. Most guides are calling to max this first, and again, I disagree. I have never had any problems keep both myself and my lane partner topped off with the first rank. You will need more ranks once team fights start however, which tends to be once everyone is about level 10. By this level, you have rank 3 and will be ready. Of course, you can not play a super aggressive lane phase, but you never should be anyway.
E: Song of Celerity
This gives you a burst of speed on activate and a static boots afterwards. I grab one point in it at level 4 and the max it last. The static aura caps at 20 speed boost, which will more or less span the gap between slow champions and fast ones (range from 300 to 325), however, the primary use of this skill is the initial percentage based boost. The 8% that rank one gives will be plenty to hold you over until your other skills are maxed. Rank 1 will give you enough edge that if you are running, you will stay ahead in most circumstances.
This is your ultimate, of course you will skill it at levels 6, 11, and 16. This is a skill shot attack that is aimed in front of you. It travels in a straight line while having a very nice range and width. This will make you opponents "dance," working very much like a stun. You should hit as many enemies with it as you can in team fights. It is also very useful to "dance" an enemy if you need to help a teammate escape. The cool down is relatively short so don't hold back if it will make a difference. The damage is fairly lackluster, so don't use it for that reason, use it for the disable.
I hope this helps, and I hope that you have as much fun playing Sona as I have ^_^