Armor enchantment summary

There are many different enhancements that any base armor type (see light armor, medium armor, or heavy armor) can be found with. The properties can be categorized into several groups. While a piece of magical armor can have properties from one or more of these groups, it will never have more than one property from the same group.

Masterwork
A masterwork piece of armor is not technically magical, just an high-quality item. Because it was made with such skill, it isn't as cumbersome, reducing the Armor Check Penalty by 1.

Material Types

 * Mithril - 50% lighter, +2 max dex, -3 armor check penalty, -10% Arcane Spell Failure chance, and armor is one category lighter for proficiency purposes.
 * Adamantine - more durable, extra damage reduction, penetrates damage reduction (rarely useful on armor)
 * Darkwood - non-metal, immune to Rust Monsters, yet harder than wood.
 * Flametouched Iron - +2 saves versus Evil Outsiders.

Magic Armor Enhancement bonuses
In general, magic armor protects the wearer to a greater extent than nonmagical armor. Magic armor grants an armor enhancement bonus to armor class ranging from +1 to +5. Armor enhancement bonuses stack with regular armor bonuses (and with shield and magic shield enhancement bonuses). All magic armor is also masterwork armor.

Magic Armor Special Abilities
In addition to an enhancement bonus, armor may have special abilities. Special abilities usually count as additional bonuses for determining the market value of an item, but do not improve AC. A suit of armor cannot have an effective bonus (enhancement plus special ability bonus equivalents) higher than +10. A suit of armor with a special ability must have at least a +1 enhancement bonus.
 * Spell Resistance - casters rolls a d20 + caster level vs resistance to affect you.
 * Elemental Resistance - confers resistance to one given elemental damage, either Fire, Cold, Acid, Electricity, or Sonic.
 * Hammerblock - confers 5 points of damage reduction to bludgeoning attacks, 2 points for the Lesser version.
 * Axeblock - confers 5 points of damage reduction to slashing attacks, 3 points for the Lesser version.
 * Spearblock - confers 5 points of damage reduction to piercing attacks, 2 points for the Lesser version.
 * Fortification - confers a chance to negate extra damage from sneak attacks or critical hits.
 * Stability - Grants the wearer +2 AC and +2 to all saving throws if they are true neutral alignment.
 * Invulnerablity - confers 5 points of damage reduction to all attacks except magic, 2 points for the Lesser version.
 * Twilight - reduces the Arcane Spell Failure chance for the armor by 10%.