[{quoted}](name=Linna Excel,realm=NA,application-id=3ErqAdtq,discussion-id=ETskBXdt,comment-id=00030000,timestamp=2017-10-19T21:31:01.960+0000)
This is interesting because statistically speaking, completing an seraph's on Sona is one of the highest winrate items.
Now Sona does have one of the better early game mana regens, so ardent is good on her until it gets nerfed. Still, having that large mana pool feels nice too at times.
Tear is something I might try in ARAM or in the RGMQ, but in my experience I would never rush it over your core support item. (I highly value my sight stone.) And it's less effective if you build it afterwards. (Also I never rely on big budget items like Seraph's anyway)
Personally, I plan ahead on what Items I will build, and build the mana components of those items. That is to say, If I plan to build both Arden's and Redemption, I would likely end up with 3+ fairy charms in my inventory. (Which isn't that much gold)
This might be my load out after completing my first eye item.

Followed by

Then possibly like

The game tends to end before competing Lichbane, or a 6th item. (Gives you space for a control ward, right?) And because of CDR from other items, I forgo Lucidity boots for a boot item with better MS.