The main reason why i like this build is that it allows you to support and heal with bursts and also stay alive in a team fight. i want to continue to improve this build so i would appreciate comments and tips to do so.

The resaon i chose these masteries is so that i can have the cooldown reduction from sorcery and also the cooldown reduction for the summoner spells and experience boost from the utility tree. i used to use 0-9-21 but i recently switched. i feel its more important to have the Cd reduction then the small survivability from the defensive tree.

I getAria of Perserverance first so that i can leash for junglers and then also give them a heal so they can go through the jungle rotation quicker and safer. I than proceed to max out my heal first so that i can make sure im able to keep my lain alive. Most sona players i know like to lvl thefirst so that they can harras better but i feel that with her passive she can harras easily with ought a high lvl hymn of valor.

i like to rush a philosopher's stone first for the extra money because i focus on keeping my lain partner topped off while harassing the other team. i then get a Tear of the Goddess for the extra manna. The Meja's SoulStealer, i find, is very useful for the extra burst heal. Since u are a support you get many assists, giving you one stack each, with ought dieing. If you are able to stay in the back and give off heals and aura's you should quickly gain stacks. the ArchAngels and Rabodons are simply for the extra AP giving your heals and aura'a more of and effect on your team. I finish off with a guardian angel so that if i do die, i dont lose the stacks from all of the assists. It also gives you the boost in armor and magic resist.

Pros:
Big heals from AP
Survivability from GA
Big passive advantage to team from spells and soul shroud
dont run out of mana from AA

Cons:
She is squishy so you have to be cautious and by wards
comment more for cons, i would like to improve all i can.