Im still testing new masteries and items for Preseason changes.
I'm going to introduce to you my way of playing Sona, Maven of the Strings. I have been playing LoL about 3 years now, and I main support champions. Sona was the first support I played and I fell in love right away. I have been playing her as AP support at S2, and at S3 i changed to more of a "100% support" build. At S3 I got myself from Silver 5 to Gold 5 playing mostly supports and Sona. At the moment I have 65% (W56/L30) win rate with her.
I love Sona, because she heals well and also does quite a bit damage too. She is great at harassing and with her you and your carry have a lot of sustain. Of course she is weak at the beginning, but it won't matter long.
Item sequence at top of the page is situational and can change depending on the game, as well as skill sequence. Ill try to explain some situations at the chapters below. So it will not be always the same build at every game.
Edit 11/11/12: Changed CV as main spell on the top of the page.
Edit 12/11/12: Updated the guide for new patch.
Edit 14/12/13: Updated guide from AP Sona to Support Sona, changed introduction to match my current experience.
Playing as support
As a support, you are not there to kill champions or farm minons, you're there to support your team, heal them and try to get them safe if they're chased. At S4 with new trinkets and ward limits, its not anymore only your job to buy wards. But try to use yours wisely over the map, and ask your teammates to do so too with their yellow trinkets or other.
I myself keep helping my lane partner to get last hits on minons as much as possible, try to harass enemy carry to lose minions, but keep in mind who you are against. Your main job is to keep your lane partner full hp and always make sure you have little mana to emergency heals and let your mate know if you are low on mana so he/she dont push too much.
With Sona you will accidentally take some kills, but try to give the kills for carrys of your team. At higher ranked level fellow teammates wont rage about you getting the kill, it's good that your team got the kill at all!
Greater Mark of Hybrid Penetration
Greater Seal of Armor
Greater Glyph of Scaling Magic Resist
Greater Quintessence of Ability Power
I like the Hybrid Penetration marks, so your spells and autoattacks will get a little boost. Ability power quintessences are good as of preseason 4 because Sona got little AP ratio boost. Armor and magic resist are basics for support.
I use 0/9/21 masteries. I am still testing them and will update as i see which works.
I like usually build support tanky, that's why i have 9 points so defense tree. I think Sona does enough damage without putting points to offense tree.
From utility tree i like to take Mana regen, Cooldown reduction to summoner spells, gold bonuses, experience boost while near teammate and movement speed.
Flash is always a good choice. You can get away from ganks easily. And with Sona its usually you who gets focused on ganks.
This is nowadays a must for support. Exhaust can save your AD carry at lane phase, and its useful on teamfight when there's deadly targets.
This was a must for ranked game supporting, no much use anymore.
These are my choises, i think Sona doesnt need any else. Of course sometimes AD carry you are supporting asks you to change summoner spells to fit their playstyle. If you think its a good idea, go for it.
I start with Spellthief's Edge, Warding Totem and two wards. You can also take instead of two wards just one and some potions. I'll try to build Sightstone as soon as possible and update Spellthief's Edge to Frost Fang.
These are my core items for almost every game as Sona. Boots reduce the time of stuns, roots etc on you. Sometimes i take Armor boots if enemy AD champions are doing good. Locket of the Iron Solari is awesome with the shield active. Some junglers and top players like to build this too, so talk with your team who will get it. Frost Fang has been good item to my build with the nice slowing active. Ill change my yellow trinket to red when I build my Ruby Sightstone, because you will have the max limit of wards just from that.
Randuins is good, if enemy team has hard initiaiting AD champions. It will slow the attack and movement speed of enemies at teamfights.
I build Frozen Heart often, it gives armor and lowers your cooldowns. It will also slow nearby enemies attack speed.
Mikael's Crucible gives MR boost and also is useful if enemy team has hard AP Stun combo. Active will heal your teammate and remove all stuns/roots/taunts/silences.
Abilities and sequence
Power Chord (Passive)
After casting 3 spells, Sona's next attack deals bonus magic damage. Additionally, Sona's Auras persist for 3 seconds after deactivating and set off a 2 second global cooldown. Power Chord has an additional effect depending on which spell was cast last.
For harassement, use Hymn of valor before your passive, its best that your Valor hits the enemy and then passive right after that, it takes nice piece of squishy champions health away. Song of Celerity will slow the enemy. This is good to cast if enemy is getting away from your team.
It took some time from me to learn use these additional effects properly. But its great passive.
You can get the passive ready at your spawning pool when the game starts to get the edge at lane. Just cast your spell 3 times and you are ready to go.
Hymn Of Valor
Sona plays the Hymn of Valor, granting nearby allied champions bonus Damage and Ability Power. Additionally, casting this ability sends out bolts of sound, dealing magic damage to the nearest two enemy champions or minions. If this spell was last cast when Sona's Power Chord is ready, her next attack will do double the damage of her Power Chord.
Aria of Perseverance
Sona plays the Aria of Perseverance, granting nearby allied champions bonus Armor and Magic Resist. Additionally, casting this ability sends out healing melodies, healing Sona and a nearby wounded ally. If this spell was last cast when Sona's Power Chord is ready, her next attack will de-buff the target to deal less damage.
Song of Celerity
Sona plays the Song of Celerity, granting nearby allied champions bonus Movement Speed. Additionally, casting this ability energizes nearby allies with a burst of speed. If this spell was last cast when Sona's Power Chord is ready, her next attack will slow the target.
Sona plays her ultimate chord, forcing enemy champions to dance (stun) and magic damage over time.
Skill sequence at top of the build is usually useful. Altought it depens on situation. If you and your lane partner are losing much health, i recommend maxing heal as soon as possible. Also get at least one point to your E spell before lvl 6, since it can help a little to get away from gank, or speed your team up to get the kill.
Like I said earlier, your job is to support your mate at same lane. You keep him/her full hp as good as you can and let last hits for him. You can autoattack minions to help your buddy to kill them faster IF needed. Just make sure you always have mana for heals too, damage isnt your main job. And let your buddy know, if you are out of mana so he wont push too hard.
You can harass enemies OF COURSE DEPENDING WHO ARE YOU AGAINST. If there's not so heavy burst samage/gap closers//stuns, you can hit enemy carry with Q and passive. When for example Leona uses her Zenith Blade and doesn't hit with it, you can go harass since she wont be high threat anymore. Same with other enemy stun abilities, if they fail it you can punish them.
Use wards while laning phase is on. Usually at start I put one ward on river and another at enemy side lane bush. Keep these up at all times. Later on i will move river ward near dragon and start to ward tri bush too.
Anyhow, everytime you return to base, take at least few wards until you get Sightstone. When I still have free space for items, ill buy mana potions to keep myself (and my carry) at lane longer.
Teamfights / Saving your teammates
Try to use your ultimate Crescendo in teamfights, when you can get most of the enemies on it at once. Or at least try to hit their most lethal targets. Sona's ultimate can turn things around completely, your team can just nuke them while they are stunned.
If teamfight went badly, Ill try to get enemies to focus me so my teammates can get away. Most of the time it works; just try to run opposite direction than rest of your team to get enemies distracted. Its better than you die alone if you can save at least few members of your team.
SAVING YOUR TEMMATES
Sometimes you see your teammates in trouble. If they are close enough, you can run towards them, then use your heal and speed spells so your team mate can get away. If theres great danger, then you can throw your ulti at your enemies face and then escape with E and W. This is also good when someone is ganking you. Try to help your teammates to last breath.
Still remember to consider if it is worth to rescue them (1 teammate in trouble). Dont set yourself in danger, at least like that when you and your teammate both die for it. If you die for your teammate, that's cool. Its more important that your carry survives.