OK. So. I DID actually read. And I also think it should be Armor Seals. You should put in item explanations (check my Syndra guide for reference). I actually go Armor Seal and Scaling AP Glyph. This is because with Athene's you will have plenty of MR to fine against any AP champ. And even before Athene's, you have chalice. Rushing Athene's with Syndra is always a must as it allows for infinite pokes and unruly EARLY combos.

If you'd read through the guide, you'd know why I decided for thoses runes ect. Maybe read next time ;) Thx anyways

Getting AP seals is pretty risky. I'd pick Greater Seal of Armor instead.

double Doran's Ring and Tear of the Goddess should be mentioned, too. Athene's Unholy Grail isn't the only choice.

Rylai's Crystal Scepter isn't really core on defensive Syndra. Zhonya's Hourglass is a must on Syndra. No matter what.

Arcane Blade > Dangerous Game any time.

You can't get Unyielding if you don't have two points in Block .

Please don't use "u". "You" is much better.

You are missing information about runes, masteries, items and such.