Dude its a troll build

I just... No. Just no. Pretty much everything about the build is wrong, and the guide is poor, at best.

So, about the build. Your runes are wrong. It's not just that I disagree with them, they are wrong. Even supposing that is what you want to take, the runes would be more effective if your took HP seals and AP glyphs, because as is they are both secondary, and switched they would both be primary (meaning more of both). Also, this is probably not what you actually want to take for runes, anyway, for a variety of reasons.

The masteries as massively sub-optimal. There is no reason to put all 30 points into Utility. Both 9/0/21 and 0/9/21 (probably the latter, since you take Heal) would work far better. The extra 9 points in Utility don't give you anything really worth having: as a support, you won't get blue buff; spell-vamp isn't at all good on Sona, since to make use of it she has to burn through mana; the extra starting gold is pretty paltry, and you really shouldn't need to start with an extra potion; and the bonus HP5 is more easily obtained in the Defense tree.

The items are way too expensive to be realistic on a support. Most games, even long ones, as a support I do not end up with more than 10k gold. With your build, that puts you part way through building Warmog's Armor, which is to say a little over halfway done. And that's assuming you spend no gold on wards, which you should be doing as a good support.

Also, in your guide it seems that you farm with Sona. So either you steal the AD carry's farm, or you go mid. Neither of these are at all ideal. Stealing the AD carry's farm only really reduces your team's damage, since that AD carry with one extra item accounts for more extra damage than Sona with this full build; the tradeoff is not at all proportional. Going mid is also extremely weak, since Sona only has one non-ult damage skill, and even though it has a good ratio, this makes her burst rather weak. She will simply be bullied out of lane by other champions who can deal much more damage, much faster, at a much better range, and therefore lose her lane. You also fail to explain in the guide which of these two you do, or if you do something else.

also turn on require comment to vote.

+1 good start

dont agree with your runes. the extra ap, will not benefit. you should just be getting greater quintessence of potency. work on your coding first. for instructions, check out jhoijhoi's guide on making a guide!

keep up the good work!