in my opinion is great on her. Not only do you get 100 AP and 400 health (keeps you from getting nuked as easily, but does not effect your W so careful), but the passive procs on both your Q and E making lading those snares very easy and grouped team fights allow for massive regen capibilies.
10Tickler1 votes1: It's not a /bad/ item, but remember, your heal scales off of AP, and costs %Current HP, so the more health you have, the more it'll take
JavelinJoe1 votesbut the less you have the quicker you die. I made a post about the a wile back.
10Tickler1 votesNot...not really, Focusing more on HP-regen, with a secondary focus on flat HP is a better option. Visage, then snag a Morello's or Athene's and spam your Close-range Q's. Hell, Spellvamp-raka's not bad either
JavelinJoe1 votes
is my usual core, the last item is situational
Magnum Mack1 votesI dare say I'd rather take FoTM or Locket instead of rylei's just because the hp regen will be nicer. I always preferred FQC being built first just because I like the vision aspect and the mana regen was nice.
ZZ'Rot was always a nice option too for survivability because flat health is still gonna be depleted by your heal just as quickly because it is a %hp drain but armor and mag resist will help you stay alive AND you get a zz'rot portal to freeze/push lanes and possibly take towers/inhibs.
I always wonder why I don't see more ardent in soraka builds.
cystium1 votesSlows dont stack and your Q already aplies a 30% slow for 2 seconds at level 1 with an extra 5% slow each level. Rylai aplies a 40% slow for 1s (AoE). which basicaly adds up to: an extra 10% slow for 1 second with 1 point in Q an extra 5% slow for 1 second with 2 points in Q and no benefit after 3 points in Q
in essence you only buy it for your E and i dont think it's worth it for just your E.
JavelinJoe1 votesit helps alot for me at least to keep them inside it for the root to happen
Linna Excel1 votesShe doesn't need the passive with her new Q. If you want HP and AP on her, 
is a better choice.