Punishing kick vs trip immune targets?

[carn]

http://www.d20pfsrd.com/feats/combat-feats/punishing-kick-combat
"On a successful hit, the attack deals damage normally and you can choose to push your target 5 feet or attempt to knock them prone. If you decide to push the target, it is moved 5 feet directly away from you. This movement does not provoke attacks of opportunity, and the target must end this move in a safe space it can stand in. If you decide to attempt to knock the target prone, the target receives a Fortitude saving throw with a DC of 10 + 1/2 your character level + your Wisdom modifier to avoid the effect. "

This attack doesnt use trip, instead its save or direct prone.

I read scanned over some older 100-150 post threads about prone snakes and oozes and there was no consensus. Is there consensus so far?

What happens if a snake or ooze is attacked with punishing kick?

[MurphysParadox]

A good rule of thumb is that immunity to trip = immunity to being knocked prone. So you could do the kick and push them away, but it won't actually fall over.

Alternatively you can rule that immunity to trip = no penalty to being prone and free, non-AOO causing action to stand.

Either way keeps with the idea of the immunity. Or just judge what is reasonable on a creature-by-creature basis.

[phayedead]

What about flying or swimming creatures? This is a concern that I have. Would the flying creature not fall or the swimming creature not fall, immunity to tripping aside.

[Claxon]

phayedead wrote:

What about flying or swimming creatures? This is a concern that I have. Would the flying creature not fall or the swimming creature not fall, immunity to tripping aside.

As far as I'm aware the trip maneuver does nothing to either flying or swimming creatures in general. It is one of the major weaknesses of trip builds, that they are rendered worthless against an opponent that can hover above the ground.