[RPG] Barbarian Attack and Damage

damage = weapon base damage + (Strength modifier + power attack bonus)*number_of_hands_modifier + magic weapon bonus

• weapon base damage: something like 2d6, 1d8, 1d10... It's written in the weapon's description.
• Strength modifier: (Strength score - 10)/2 (rounded down)
• power attack bonus: +2, increases by +2 for each +4 BAB (eg for a character with BAB+7 it would be +4)
• number_of_hands_bonus: 1 if the weapon is one-handed, 1.5 if it's two-handed, 0.5 if it's wielded in your off hand
• magic weapon bonus: a +X weapon gives you +X to your damages (this bonus also apply on the attack roll)

On top of that some special effects can add other damages, like sneak attack dice, weapon with the bane property or a Paladin smiting evil.

Example: Bob the goblin has a strength of 9 and a +3 one-handed scimitar. He's a lvl 1 Warrior and used the feat Power Attack.

If he hits, he will inflict 1d8(scimitar)-1(Strength modifier)+2(Power attack)+3(magical weapon) damages: he rolls 1d8 and add +4 to the result.

I know of no way for a character to choose to do less damage than they roll. Of course, they're free to use a less-powerful weapon or not use damage-boosting abilities.

Characters can, however, choose to deal non-lethal damage with a weapon that normally deals lethal damage by taking a -4 penalty on the attack (or using a weapon that normally deals nonlethal damage, like a sap. There are two Paizo-authored feats I've found to remove the penalty to attack: Bludgeoner (which removes it when using a bludgeoning weapon), and Stage Combat (which removes it for weapons for which you have Weapon Focus). The third-party feat Nonlethal Force simply removes the penalty (this GM would allow this feat).

Using a normally-lethal weapon to deliver non-lethal damage should still count as injury (it still deals damage, just of a nonlethal type), so an injury poison would still be delivered. Any other "on-damage" effect would likely come down to the precise wording of the effect. Some examples I've dealt with recently:

• Scorpion Style: since you're using an unarmed strike, this can be dealt with lethal or non-lethal damage, at the attacker's option
• Wounding weapon: this is ambiguous, but the description suggests that nonlethal damage oughtn't trigger the additional effect

Additionally, there are a number of methods of applying a poison without a traditional weapon attack:

• Poisoner's Gloves
• Poison Popcushion