Magic Armor Basics
In general, magic armor protects the wearer to a greater extent than nonmagical armor. All magic armor and magic shields are also masterwork armor and shields, reducing armor check penalties by 1. In addition, magic armor is always created so that even if the type of armor comes with boots or gauntlets, these pieces can be switched for other magic boots or gauntlets with no detriment to the armor.
Defense Bonus
All magic armors have a Defense Bonus that ranges from +1 to +10. This can take the form of an enhancement bonus on armor class when used in combat or the form of special abilities added to the armor.
A suit of magic armor’s price to buy (and cost to create) is based on its total defense bonus. In general, the market price of armor is equal to its defense bonus squared × 1,000 gp + the value of the base armor.
Spells and effects that temporarily add an enhancement bonus or special ability (such as magic vestment) do not affect a suit of armor’s total defense bonus.
Enhancement Bonus
This bonus applies directly to the armor bonus to Armor Class provided by the suit of armor. Each point of enhancement bonus counts as one point of its total defense bonus. A suit of magic armor may not have an enhancement bonus higher than +5.
Hardness and Hit Points
Each +1 of enhancement bonus adds 2 to a suit of armor’s or shield’s hardness and +10 to its hit points.
Ranged Weapons and Ammunition
The enhancement bonus from a ranged weapon does not stack with the enhancement bonus from ammunition. Only the higher of the two enhancement bonuses applies.
Ammunition fired from a projectile weapon with an enhancement bonus of +1 or higher is treated as a magic weapon for the purpose of overcoming damage reduction. Similarly, ammunition fired from a projectile weapon with an alignment gains the alignment of that projectile weapon (in addition to any alignment it may already have).
When a magic arrow, crossbow bolt, shuriken, sling bullet, or other piece of ammunition misses its target, there is a 50% chance it breaks or otherwise is rendered useless.Ammunition that hits its target is destroyed.
Special Abilities
Special abilities have a variable point cost which counts towards its total weapon bonus. A weapon need not possess an enhancement bonus to have special abilities added to it.
Additional Damage Dice
Some special abilities add additional dice of damage. Unlike other modifiers to damage, additional dice of damage are not multiplied when the attacker scores a critical hit.
Shields
A shield’s enhancement bonus stacks with a suit of armor’s enhancement bonus. A shield’s enhancement bonuses gained from its defense bonus does not add to the attack or damage when the shield is used in a bash (though some special abilities may affect a shield bash).
A shield could be built that also acted as a magic weapon, but the defense bonus and the weapon bonus are calculated separately and then added together to determine the final cost of the shield.
The defense bonus of a shield is handled in the same way as a magic suit of armor while the weapon bonus is handled the same as any other magic weapon. The market price of each is then added together to determine the final market price of the shield. The magic armor and magic weapon aspects of a shield are always determined separately from one another, except for when calculating the shield’s final cost.
Activation
Usually a character benefits from magic armor and shields in exactly the way a character benefits from nonmagical armor and shields—by wearing them. A shield or suit of magic armor’s enhancement bonus is always active and cannot normally be deactivated.
If armor or a shield has a special ability that the user needs to activate, the user usually needs to utter the command word (a standard action). Some special abilities have alternative activation methods, which are described with that ability.
Armor for Unusual Creatures
The cost of armor for nonhumanoid creatures, as well as for creatures who are neither Small nor Medium, varies. (See Armor Basics: Armor for Unusual Creatures.) The cost of the masterwork quality and any magical enhancement remains the same.