[GAMEPLAY] Cassiopeia's W freezing minion waves

During a custom game I was testing the ap changes for patch 6.9 as well as trying out the new when I realized that when i used her W at an incoming wave it would freeze certain minions in the wave that were in mid attack animation leaving them motionless until the minion was killed. Now im not sure if you need to aggro the minions then have them run into the initially casted W that causes the freeze or if you can just cast while they run into it since it worked either way.

Steps to repeat:

1. Load into a game with
2. Pick W as a spell
3. As the minion wave begins to walk forward cast the W right in front of the minion wave
4. The initial minion(s) that were hit by the spell should freeze in place.

I will try this again to see if it was just the game lagging and will post on this feed if it occurs again. (Please test as well)