I would like to note here that I'm still writing this guide, so more information is yet to come.

Let's start with some word on why should you even pick Sona as your champion of choice. Sona is a master of pocking. using her , a player can easily take the enemies health bar to almost zero. adding to this her for healing, and her , and you get a really strong chaise/run attacker who can sustain herself almost in any situation. plus, lets not forget her with it's awesome stun, to deal with those nasty assassins.

Now that we understand why you want to play Sona, lets talk about this guide.
This guide will try and take you out of the known meta, and give you a tool to win a match ups that you will usually loose due to lack of tanks in your team.
to current meta is the Tank Meta and as a result, the game gives favor to a team with 2-3 tank in it. most of the guides for assassins, mages and adc-s, will send you in the path of maximum ability/attack power. while this guide will let you use the best items combinations with the basic skills and abilities that Sona has to offer.

I would like to add here, that i write this guide with the thought in mind, that it's hard for people to get used to a new set of mind, and therefor will try to use this guide in Bot lane as a apc/supp. with that in mind, i added some notes to how you can use this guide in the Bot lane, playing with an adc as your duo.

Lets talk lanes.
traditionally Sona plays the support role in Bot lane. you could still play Bot lane with this build but as apc and NOT support. playing support with this build, will take away from your team most of the vision in the map, and will leave you open to ganks.
As this build is made to defeat tanks it's highly recommended that you take top lane. Remember that you are a strong poker, as a result you can lower your opponent hp and make him b to base. If you manage to do that, start roaming and help mid lane or your jngl-er.
With this build you can play mid lane as well, but you probably shouldn't. you can poke, and have a stronger attack than a support Sona, but you are still a little slow and squishy, and early game might be really hard vs fast assassins like , or .

So lets start...

We have a basic start with 2 and a . i use it for most of the times, it gives you the extra starting damage that can give you an early start kill, and the mana reg.,plus the mana from killing minions, to sustain yourself.

if you chose to play Bot as apc/supp and not Top, you should start with spellthief edge, two and one . (*I should add here, that this is a strong Bot lane combo, but you should probably not play it, as mentioned in the introduction.) This will let you gain cash while not stilling the farm from your adc.
you can also use this start while playing top to get cash faster and get ahead of your opponent early in the game.

You need to remember a couple of thing: first your a little slow. second, as in any other Sona build, getting to 40% cdr (max cdr capacity) is top priority. therefore your first back item should be , and for the extra attack power.
your next goal is to buy , for the 15% cdr. so if you have 1000+ gold in your first back you might want to invest them in the boots and wait with the tome for your next back.

from here we start to build up for your core items.
you want to get as fast as you can. it's passive is really strong with sona, and firing a basic attack with it, after using , and with Sona's passive active, can be devastating to your opponent.
from there we move on to , for the extra damage and movement speed.
by this time you should notice that you have a really big mana problem that make you go back to base all the time. so your next item should be the . with that in mind, if you already have the 900 gold, you'de like to finish building your . if you dont have 900 gold, start building the chalice by buying x2.

After this you should start building your core items.
finish and that will put you at 40% cdr. start working on by buying .
Liandry is one of your more important items. first of all you get +15 magic pen., and it's second passive will destroy a tanks health. here I'de like to add a tip. try to use your Q on the enemy after after hitting him with a purple power chord, in order to slow him down and get the double damage from Liandry.
In order to finish your tank destroyer you would like to get , his passive will make it so you wont need to hit your opponent with a purple Power Chord in order to get Liandrys double damage effect. more over it will add another 100 ability damage, and 400 hp that will make less squishy.

Situationals:

- my fave 6th item. this will hammer down the last nail in your opponents coffin. a lot of tanks have a life reg. and healing items. this will cut their healing by half, give you extra 80 AP and most important, will give you another 20 cdr that will let you sell the and buy or .

- if the enemy team bought MR items and you need the extra pen. plus it has the extra 80 AP as well.

abbysal scepter - in case your enemies bought MR items and have a strong AP that's giving you some trouble. also have 70 AP for some extra force on your bite.

- most of the tank you will face will be AD champions therefor the extra armor should come in handy. also the active of the Zhonya is really helpful when your getting attacked by more than 1 or 2 players and your ulti is just not enough.

- If you did go to the Bot lane apc/supp role (shame on you), you should take this as you last item after taking as you first or second (after the ionian boots) item.