Building Assassin Sona
So I bought Sona a while back and I noticed her damage is very heavy due to her passive. So I decided to experiment a game where I had my friend and I go Sona + Morgana Duo bot. Laning phase was great, we poked a lot and constantly saved each other from ganks and such. She could stun, I could heal, we were both heavy on damage, etc.
So my build in order was
(I didn't need Iceborn in laning phase because morg's stuns), then
for cdr. I then ended up trading
for
. Too much damage lol
then

for the bonus damage on hit and bonus range.
then 

and magic resistance in early game like
which fucks you until you have void staff