Orianna support

So this patch grail was changed to give 5 AP per every 25% base mana regen you have.
I tested this on another game as Orianna support and it did very well in lane with the shielding and slow from w, only down side is mana cost is hefty early on.
So after getting four items
all with mana regen I ended up with around 350 AP which was actually enough to 1v1 a squishy skipping shoes since I wanted to stack my grail passive, I went sorc shoes after though.
I ended up with six item and a death cap as my last item along with sorc shoes, ended up with about 530 AP with an elixir, provided a lot of utility during team fights while being a threat to any squishy. Also had enough burst to chunk the adc almost 90%. If the game went on really long I would've replaced sorc with Void Staff but didn't happen.
So what do you guys think, Orianna too good or is grail overtuned? Or any other concerns.
offers additional a bit of utility for an offensive support build. Spreadshot helps find stealthed enemies, slows others (makes ults easier to land), and provides some decent manaless waveclear.
For a more utility oriented slot. 100% base mana regen also feeds into Athene's for +20 AP as an added bonus.
If you can snag first blood, Tear can sometimes be a decent buy. Keeps your mana pool healthy through midgame where you start being impactful. Seraph's shield will also work nicely with all those Forbidden Idol items you've got built up.
should destroy that lane.