Non-lethal damage does not reduce a creature’s Vitality, but instead increases their Torpor.

A creature’s Torpor is normally 0 if they have not taken non-lethal damage.

When a creature takes non-lethal damage, their Torpor value increases by the amount of non-lethal damage taken.

When a creature’s current Vitality is equal to or below their Torpor, they fall unconscious.

When a creature’s Vitality is healed, they also lose that much Torpor.

Normally, only bludgeoning damage, some sources of toxin damage, and some spells can be non-lethal. You can use a non bludgeoning damage weapon as an improvised weapon attack to deal non-lethal bludgeoning damage as well.

To deal non-lethal damage, you must declare your ability as non-lethal, if it does not explicitly say so already on the ability.

When a creature is knocked unconscious in this way, they remain unconscious and cannot attempt to wake for 1d20*6 seconds, even if they take damage, unless their Torpor returns to 0.

When a creature would attempt to return to consciousness, their Torpor is halved. If their torpor is still higher than their vitality upon attempting to wake, they fall unconscious for another 1d20*6 seconds, even if they take damage, unless their Torpor returns to 0.