How many balls can Syndra have?

The new champion Syndra in League of Legends uses a skill named Dark Sphere to place these cool balls of anti-matter on the field. The balls last for 6 seconds and the cooldown of the ability only easily allows for 2 balls on the field at a time. This is important because her ultimate spell, Unleashed Power does more damage based on the number of balls on the field at the time of cast.

Now her second ability Force of Will allows her to grab a ball, refresh its duration to 6 seconds, and throw it at something. (In that order)

Now I have cleverly managed to get 3 balls on the field at any given time but the wiki strongly hints that there can be 4.

How many balls can I have and whats the spell order \ CDR requirments to achieve them?

Solution 1:

Using Force of Will to refresh your first sphere as it's about to expire, it's possible to have four spheres up at once for a brief moment.

Assuming no delay, a Dark Sphere cooldown of 3.0s would mean that your second sphere would disappear at the same instant as you're about to cast your fourth, so clearly you will need a lot of cooldown reduction to pull this off.

Here's an example timeline at maximum CDR (40%, 2.4s Dark Sphere cooldown).

                        Remaining time on sphere #
  t                       1      2     3     4
 0.0s  Dark Sphere      6.0s     -     -     -
 2.4s  Dark Sphere      3.6s   6.0s    -     -
 4.8s  Dark Sphere      1.2s   3.6s  6.0s    -
 5.8s  Force of Will    6.0s   2.6s  5.0s    -         
 7.2s  Dark Sphere      4.6s   1.2s  3.6s  6.0s

Again, this is without accounting for delay, so it will be tighter than this in practice.

Also note that you have some flexibility in when you want to use Force of Will, as long as you use it some time after casting your second sphere and before the first sphere expires.

_{Note: I'm currently not able to test this in-game, so this is pure theorycrafting.}