Ofcourse, all credits to finding this go to SimplySarc: https://www.youtube.com/watch?v=aZp9olUXvOY
My video demonstration: https://www.youtube.com/watch?v=76XobG9QdOs
What is happening: When the Ravager attacks an entity, and that entity is shielding, he has a 50% chance to roar. For the first two seconds, he is stunned. After another 0.5 seconds, he roars, knocking back players within 4 blocks of him.
The math to apply the knockback is as follows: