Re: Knockback against opponents with Flight, Clinging, Catfall
 

You're referring to their sliding across the ground?

A person subject to knockback would continue to travel through the air for several seconds only if the target was launched on an upward trajectory, or if the ground sloped down. Because of the vector addition of acceleration and velocity, motion can be decomposed into orthogonals. So everything from a dropped stone to a bullet fired parallel with teh ground takes the same amount of time to hit the ground: the difference between the bullet and the stone is only how far they travel horizontally in the time it takes them to fall.

So it is with knockback. Unless you launch people upwards they take about half a second to hit the ground, regardless of how fast they are flung away.

Re: Knockback against opponents with Flight, Clinging, Catfall
 

And it should be noted that this attack is the equivalent of the amount of knockback caused by a 2d x 20 crushing attack. That should cover any damage you would realistically take as part of the sudden impulse you were experiencing.

Re: Knockback against opponents with Flight, Clinging, Catfall
 

Since we have rules for this (B468, Bailing Out of a Moving Vehicle), why not apply them to this situation? In other words: "a collision with an immovable object, at the vehicle's speed."

If it's good enough for falling off a motorcycle, it should be good enough for getting knocked off your feet by Tornado Punch.