If you play sona ,YOU ARE SQUICHY ! SO YOU MUSN'T BE ALONE From the beginning to the end og the game , your comrade is the only thing wich make you survive and if he do it you 'll support him/make kills /have lots of gold so you musn't be with a tank , in the beginning you'll burn all of your mana for healing him .

Your best weapon .... :your power chord , miximize by lich bane

I think that my runes are like they have to be.

9/O/21
9 : you are a support/caster so you need to strike through ennemys stuff so Go for Archaic knowlenge with 3 in archmage savvy for bonus AP , 1 in critic cuz you need 4 to reach the next step , 4 in CDR and 1 in insight bonus

21 : You don't want "presence of the master " because your sumonner's spells are useless during a team fight and you'll have enouth mana in the end SO i choose to maximize : mana pool , health pool ,teleportation speed , XP gained , Greed , mana regen , clarity ,CDR , and movment speed (1/3)

Support : greed , clarity , XP , movement speed (heal )
caster : mana pool , regen mana , CDR , AP bonus , Insight bonus

You need lots of mana so first item , tear of the godess , (don't forget to farm it )
You are OVER-Squichy so run fast , and as you know , your CD (5") are really long if you have to heal or kill ... so ..... : boots of lucidity
Now , You need AP and money so kage
You wan't to kill now so sheen for it's passiv and mana pool after that , lich bane , same reason
Now you really really want to kill so death fire grasp , for AP and activ wich is really usefull!
Now finish your archangel's staff and you will have more AP again
For the same reason than last time , rabaddon's cape and rylay'sscepter for it's passiv and health

In the beginning don't attack if you don't have your power chord antifarm ennemys with it so don't be greedy with mana .
Farm as soon as possible .
Always heal your comrades untill they are full life .
you'll be focus every moments , so stay back and strike hen TF are engage .
Use your ult to protect your allys or for gank .

See You !