Not Updated For Current Season
The masteries shown here are not yet updated for the current season, the guide author needs to set up the new masteries. As such, they will be different than the masteries you see in-game.
4 sphere combo. Quick fire solution, useful for snap reflexives and virtually no setup costs. Generally not recommended, its damage potential is low enough it's hard to finish off most kills unless literally ANYTHING would kill them at that point.
+ ++ (Q+W+Q+R)
5 sphere combo. Your workhorse and most often used combo. If CDR is quick enough, two Dark Spheres can be placed down then fired off. If you want more time, or wish to setup for a 6 sphere combo, use Force of Will to grab the first Dark Sphere placed down and reset its life timer. Be sure to throw the sphere, as Unleashed Power doesn't use held Dark Spheres for its damage.
++ + + (Q+Q+W+Q+R)
6 sphere combo. You must grab the first Dark Sphere dropped down with Force of Will to refresh its life time while casting the 2nd sphere. Throw the sphere held by Force quickly, cast a third Dark Sphere, then fire Unleashed Power immediately. This can be done at 5% / 10% CDR at around level 6, but the timing required is VERY close. It'll become much easier once Athene's is bought, however.
+ +++ + + [img=http://www.mobafire.com/images/ability/syndra-unleashed-power.png(Q+Q+W+Q+E+Q+R)
7 sphere combo. Drop the first Q, then the second, then the third. Immediately grab the first when the third is put down, throw it, then put down the fourth. You have about 0.5->1.2 seconds to fire off all 7 spheres with Syndra's ultimate. This combo REQUIRES 33%~ CDR bare minimum and is impossible to do below that threshold. It becomes easiest to do at 40% CDR (WOTA+Athene's+Runes/Masteries, or Athene's+Runes/Masteries+Bluebuff).
If you're attempting this combo, you are very deliberately going to cash out on it no matter what. You have no room to pick or choose if you're going to use it, otherwise you have to ramp up all her spheres again for another 7-9 seconds. It's not unreasonable to get the seventh sphere, then Flash+Ult, and force a fight/kill in the process.