[GAMEPLAY] Sivir's Spell Shield (E) Casting Time is Highly Variable

When using Sivir's Spell Shield (E), the actualization of the shield will sometimes be delayed by up to a few tenths of a second, which is highly variable when the ability is one that is almost always used as a reaction. The activation of the ability (the moment the ability goes on cooldown) is not delayed, as far as I can tell.

How to Reproduce: Step 1: Enter a game as Sivir (preferably practice mode, so you can spam E) Step 2: Activate Sivir's Spell Shield (E) and note how long it takes for the ability to trigger Step 3: Repeat step 2 until you notice that the trigger times are indeed varying

Be sure to avoid maintaining a rhythm of activating Sivir's Spell Shield (E) when initially testing for the bug, as it seems to either prevent the delay from happening or causes it to occur nearly each time.

The Bug appears on the PBE servers as well, however it is slightly less noticeable for me, as my ping is more than two times higher on the PBE servers (33 ms on normal servers and 76 ms on PBE servers).