League-of-legends – Does Chaos Storm silence 0.5 seconds constantly

It's because we're used to the other acronyms of HP5 and MP5, and well, 5GP10 is too weird.

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.}