http://www.youtube.com/watch?v=eQK-N6Lluh0

Runes are quite easy:
-Scaling ap for lategame power
-Ap glyphs for early pressure
-Mana reg. seals to survive midlane before your chalice of harmony
-and ap pen. to penetrate the enemy^^

This is a Build focused on lategame. Syndra is a lategame champ and if you loose early in midlane, play defensive. You´ll put the enemy ADC out of teamfights and make him "useless"

if you invade: prob lvl W do drag and drop their buff
but normally q for early pressure
then e, to survive an early gank or fight/trade

then first max q to deal even more dmg to champions when maxed
second is w to gain the bonus slow
third is e, cause you dont get that bonus when maxe.
and like everytime the ult, whenever possible

My masteries allows you to deal heavy dmg and also roaming with the bonus mvm speed.
but you can use your own masteries and playstlye:)