syndra is very awesome champion but i see , theres more better building items .. you can start with doran's ring for more ability power and also mana regen on killing minions .. 

Athene's Unholy Grail would really solve Syndra's mana problem till end of game .. and focus on have 40% cooldown reduction to have max reduction for all her abilities and also it help lot to Ultimate with 6 balls with can equal to 900 damage if u have only 300 ap :) 

i tried it and it really worked .. and about her counters .. Talon and Kassadin is very good counter to her .. Else i dont think so :) 

After playing a LOT of Syndra, I can definitely say that basically anything with high mobility (especially jump abilities, ie Kat, Talon, etc) typically counter out skillshot based champs like her. People like Zil can be countered with a banshee's veil, or other item(s). High CDR is definitly a plus, and stat priorities for her i'd prob rank at:

mPen>CDR>mRegen/HP>HP/mRegen>MoveSp

For itemization, Blackfire Torch is definately the best item to grab on Syndra and I rush it in all maps applicable. For Summoners Rift however and Liandry's Torment, I usually start with boots+pots and rush Haunting Guise or a chalace if I can tell it will be a farm lane/ or a onesided duel against more burst than me/ ...or im just harassing them out of lane so well that i want to keep them out longer lol. Haunting Guise + PenBoots gives a great ammount of early-mid spell pen, and from this point I'd either try and keep blue buff on me and either start building a deathcap or Rylai's Scepter. Rylai's + Liandry's Torment gives you the tanky damage you need against higher burst teams, or very tanky teams that are hard to burst down. From here you want to finish your chalice (ive been prone to entering mid game with penBoots, HauntingG, ChalaceOfH, and a codex for the extra CDR. 

On Syndra, if you can afford it and are getting extremely fed, the IDEAL burst to death build would be:

---Average enemy team: Boots > HGuise > penBoot > NLR/ Full Deathcap < > DFG*  (DFG gives more burst than Deathcap on one target imo, mainly because it does %based damage + buffs your burst. This helps a lot on TANKY teams or teams that have good escapes where you need to burst from full to dead in under 2 seconds...)

--Tanky / Bursty enemies / your team sucks: Boots > HGuise > penBoots > Chalice > Codex/GiantsBelt > Rylai's, Liandry's and Grail (in whichever order you need, wheather you need more cdr, hp+slow, or %based damage). From here you can decide on what your final items should be, either one Defensive and one Offensive, or 2 def / 2 off. Good items being, banshee's veil for burst teams or teams with strong single target abilities, deathcap for more rounded burst, Zhonya's for armor, ap and utility (syndra has low cooldowns at max level when built proper, that couple seconds of stasis can AND HAS BEEN the deciding factor in getting aced or scoring a pentakill), or even a Void Staff if the enemy team recognises the danger you bring and has begun building MR.

As for dealing with high-mobility characters, there's little you can do buy build the tankier route, though if anyone has any additional opinions on this i'd be glad to hear suggestions.

Updated build eh? Starting with flask five pots ward and mana pot seems a tad outdated to me...

Great farming champion and easy to last hit with his AA's animations

Pretty sure Syndra is a she...

This guide needs to be updated... with the increased cost to Crystalline Flask, is it still worth buying?

Also, is it really okay for Syndra to only get Athene's after Liandry and Archangel? does she needs both? 

For cristalline flask, yes it is still worth it.

No offense, but this guide is really "bare bones".

Tips and tricks...  use the W to help farm at tower if you get pushed in - you can snatch minions away from tower shots, then throw them + auto attack to get the CS, as well as hit other minions to get CS.

Use W to lead into your Q's. Grab minions, throw them to damage + slow, then Q on top of enemy heads.  Throwing a minion isn't expected as much as throwing a sphere after you've dropped one already.  And its a quick double tap with smart casting to drop the W on their heads and follow with a Q.  its a lot of harass damage, more than people expect. 

Use W to kite - you can W while running.  Drop a sphere in front of yourself as you are running away, grab it with W and throw it behind you.  instant slow.  Do the same with minions as you run away. 

Use W to set up skill shots for your allies.  If there is a minion blocking an amumu bandage, GRAB THE MINION.  Same with lux bindings, morgana bindings, etc. etc. 

W vs E:  I prefer maxing W second, because even with rank 5 and cooldown reduction, cooldown on E is 10 seconds, you can't rely on getting more than 1 in a fight (especially if you save it for mid-fight rather than leading with it).  So rank 1 in that skill is all you need for utility, and relying on it for damage is pretty poor. 

my opinion:

after u maxed dark sphere u need to max force of will....u need scatter the weak only for stun -> a lot damage u make by q and w

my combo :  Dark Sphere + Force of Will +Scatter the Weak+ Dark Sphere +Unleashed Power  = no one can survive)

owned all of her counters , haven't played against veiga can't tell u brene

 GL

Veigar counters almost every AP smartass. I would be pretty pissed if they would mention veigar on almost every shitty Champ.

Actually, you can counter veigar by just gameplay, so he really isn't  a  hard counter to any champion...

 You can itemize against Veigar to some degree on all AP champs - start with penetration items more than straight AP, - sorc boots/Mask/abyssal - and dual MR/AP items - for the laning and mid game phase.  If you just go straight for a deathcap against a veigar, you better be skilled enough to outplay him and not get 1 shot by his ult, and that's on any AP champ.  Syndra has strong enough base damage on her Q and W that this works pretty well, and since veigar will sometimes grab an early chalice for mana and MR, the extra Mpen is even better. 

May be a small change, but I would switch force of will and scatter the weak early point distribution.  The slow from force of will is nearly as good for avoiding ganks, and your harrass with the 1-2 combo of sphere/will is much more reliable and usable. 

force of will doesn't stun them, but it also doesn't require a prepositioned orb in just the right place for a stun.  And the harass potential of will is really nice.  It both does the damages and almost gaurantees your sphere will land. 

Dunno wether I should go Grail or RoA first...Both give Mana (sustain). Both make you beefier (though indifferent ways). Grail gives CDR and more AP. RoA grants HP sustain...