[GAMEPLAY] highlander giving immunity to all cc

I recently played a game where highlander was making master Yi immune to all cc (specifically Irelia's equilibrium), i have encountered this bug many other times with master Yi, so I am assuming that it is not an Irelia bug. also this happened when the Master yi had 50% health and I had less than 10% so I'm also assuming that it was not a mechanical error on my behalf

1. Play master yi.
2. Press r.
3. Have much higher %health than Irelia.
4. Have Irelia attempt to stun master yi.