When you score a critical hit or a successful Stunning Fist attempt against an opponent while using this style, that opponent is also shaken for a number of rounds equal to 1d4 + your Strength bonus.
Since the Shaken given by Dragon Ferocity doesn't seem to reference the Intimidate skill at all, I believe you can stack the Shaken effect from multiple criticals(or multiple stunning fists) to make an opponent Frightened or Panicked.
But what if you hit someone with a successful Stunning Fist, and the attack that delivered the Stunning Fist also happens to be a critical hit? Do they get Shaken twice, becoming Frightened immediately? Or are the only Shaken once, because they've only been hit by one attack(which met both qualifiers?)
Thaaaaat's a lot of assumption making
Unless it specifically says that it stacks, it doesn't
And again, unless it specifically says that there's some additional or stronger effect when you crit, it doesn't.
Shaken: Characters who are shaken take a –2 penalty on attack rolls, saving throws, skill checks, and ability checks.
Frightened: Characters who are frightened are shaken, and in addition they flee from the source of their fear as quickly as they can. They can choose the paths of their flight. Other than that stipulation, once they are out of sight (or hearing) of the source of their fear, they can act as they want. If the duration of their fear continues, however, characters can be forced to flee if the source of their fear presents itself again. Characters unable to flee can fight (though they are still shaken).
Panicked: Characters who are panicked are shaken, and they run away from the source of their fear as quickly as they can, dropping whatever they are holding. Other than running away from the source, their paths are random. They flee from all other dangers that confront them rather than facing those dangers. Once they are out of sight (or hearing) of any source of danger, they can act as they want. Panicked characters cower if they are prevented from fleeing.
Becoming Even More Fearful: Fear effects are cumulative. A shaken character who is made shaken again becomes frightened, and a shaken character who is made frightened becomes panicked instead. A frightened character who is made shaken or frightened becomes panicked instead.
Fear effects are cumulative. A shaken character who is made shaken again becomes frightened, and a shaken character who is made frightened becomes panicked instead. A frightened character who is made shaken or frightened becomes panicked instead.
So you can make a Shaken foe into a Frightened foe using Dragon Ferocity.
I'm not sure what happens if you use a Stunning Fist and Critical Hit using the feat however.
Ah, guess that's true, my bad