Hello, to preface this is all based on my memory of somewhere being written that if an attack or similar thing deals 0 damage (mainly in the course of it being reduced to 0 through resistances and such) that any abilities attached to it do not "go off" or activate/happen.
The situation is this:
My players were accosted by a roc. It has Improved Grab, which allows it to use Grab as a free action as part of its talon melee strike(s).
The roc used Flying Strafe and attacked two party members. It succeeded against 1 and missed against the other. It used Grab and then the Snatch ability activated automatically allowing it to move half its fly speed while grabbing or restraining a creature.
To the point, the player was able to use Shield, reduce the damage from 19 to 4 (15 hardness) before any resistances applied, and was under the effect of Inspire Defense at 6th level (3 phys. resist). That still meant 1 damage. She was carried up and away. (don't worry she lived)
However, I'd like to pose a hypothetical: say the res. was 4 and she took 0 damage. Technically Grab says only that the "previous Strike was a Success", not necessarily that it needs to deal damage. Would the Grab still go through, even though no damage was applied?
I want to say yes, but I'm unsure if there's an over-arching rule that calls attention to something like abilities where additional effects it only activate if at least 1 point of damage was applied per the ablity or attack triggering it.
I'm not aware of any such rule. An effect only cares about damage if it says it does, like Vicious Evisceration or Knockdown.
VICIOUS EVISCERATION [two-actions] FEAT 18
BARBARIAN RAGE
You make a vicious attack that maims your enemy. Make a
melee Strike. If the Strike hits and deals damage, the target is
drained 1, or drained 2 on a critical success.
KNOCKDOWN [two-actions] FEAT 4
FIGHTER FLOURISH
Prerequisites trained in Athletics
You make an attack to knock a foe off balance, then follow
up immediately with a sweep to topple them. Make a
melee Strike. If it hits and deals damage, you can attempt
an Athletics check to Trip the creature you hit. If you’re
wielding a two-handed melee weapon, you can ignore Trip’s
requirement that you have a hand free. Both attacks count
toward your multiple attack penalty, but the penalty doesn’t
increase until after you’ve made both of them.