eamon
Explorer
If a creature is capable of shifting when an opponent is on top of it, why isn't it capable thereof when no opponent is on top of it?Perhaps if you stand up from prone with an enemy in your square he could just decide where you have to shift freely, making it more balanced instead of an AoO.
I don't see the big balance problem with simply banning the shift, and permitting an OA-provoking 1 square move. Frankly, it's really lenient to permit a creature to be unconcious, wake up, stand up and move 5 feet all within a single move action in 6 seconds without provoking.
Another problem with the push or forced shift mechanic is that in general you can always push someone fewer squares. Or you push toward blocking terrain (and fail). What happens in these cases?
I think it's reasonable to penalize creatures for being in a horribly disadvantageous situation, and it's unreasonable to deny them these stand up abilities merely because they weren't helpless and there's no enemy standing on top of them. If you're really worried about prone being impossible to escape, grant some expensive action - say, if you use a standard action to stand up, you may shift a square - something, in any case, which makes it unattractive to use in normal situations so that you're not stuck with the inconsistency that only creatures with enemies on top of them (meaning they were helpless) can somehow stand up and move without getting hit.
I don't think there a balance issue with penalizing helpless critters being straddled by their enemies, and I think there is a consistency issue with penalizing those that weren't helpless and straddled.