PvP Rath can use Catalytic Smash to knock a player into the air, then move under the player while activating Dreadwind to prevent him from returning to the ground due to the collision physics in the game. Basically, the player gets stuck on Rath’s head while he spins, completely unable to perform any actions whatsoever.
This wouldn’t be much of a problem, but while stuck on Rath’s head, Dreadwind still deals insane damage for an easy kill. This is not the same as CC; this is an exploit.