Stack

Abilities or skills that "stack" add their effects together. For example, modifiers of +1 Save all and +2 Save against fear "stack" to create a total +3 to Save versus fear (in addition to the +1 to Save against everything else).

Abilities or skills that do not stack apply only the strongest effect. For example, having non-stacking +3 and +5 modifiers is only worth a +5 bonus, not +8.

Stacking follows a few predictable general rules:


 * Bonuses usually (but not always) have a keyword, such as "enhancement" or "resistance", identifying what type of bonus it is. Bonuses of the same type do not stack.
 * Dodge bonuses to AC are a partial exception to this. Dodge bonuses stack unless they're the same size and both come from worn items.
 * If your armor and your shield both have enhancement bonuses to their AC, those also stack.
 * An "armor bonus" does not stack with actual armor. A "shield bonus" does not stack with an actual shield.
 * Untyped bonuses stack.
 * Penalties stack.
 * Feat bonuses stack. A character with Lightning Reflexes (+2 bonus to Reflex saves) and Luck of Heroes (+1 bonus to all saves) will have a +3 Reflex save.
 * Bonuses from character Enhancements are almost always untyped, and thus stack. They are not automatically "enhancement bonuses". Note, however, that some Enhancement lines are mutually exclusive and cannot stack because they cannot both be taken.
 * Benefits from the same family, like Fortification or False Life, do not stack.
 * Damage Reduction does not stack, except for the added DR that comes from active blocking.
 * If you use a bow or crossbow, bonuses and properties on your weapon do not stack with ones from the same category on your ammunition. For example, using +3 bolts of lesser undead bane in a +1 flaming crossbow of lesser undead bane gives your shots +3 to attack and damage (not +4), flaming damage, and the normal (not double) lesser bane effect.