League of Legends (LoL) Question: Is tear of the goddess viable on Sona?

It's okay but I don't see a good reason to build it over philosopher's stone and/or Chalice of Harmony. It takes a lot of time and gold to upgrade the tear into Seraph's Embrace, so basically you're just buying mana regen. You might as well get a chalice if that's what you want, since it builds into more realistic support items and gives some MR.

No IMO Nomad's Medallion builds into your support items and it will take longer to get your Sightstone.

In ARAMs it's fantastic. In Summoner's Rift, I'd say no. Dominion, yes. Twisted Treeline, possibly.

Support sona i feel like it kinda sets you back but going ap mid sona i feel building it into the archangels gives you stats that are worth it

My answer is yes.

it's 180 gold cheaper than Chalice of Harmony, both solves your mana prob if you spam Q or W harassing or healing.

Tear of the Goddess gives you huge amount of mana which is better than Chalice of Harmony because with chalice, you'd still go OOM and have to wait for it to regen, with tears, you can spam a lot an not run out of mana easily.

Do note, that even if tear is cheaper than chalice, athene's unloy grail is easier to build than archangels' staff because of cheaper component that come in parts.

But I don't recommend upgrading either because as a support you have other more important items to buy than either Athene's Unholy Grail or Archangel's Staff.