Armor AC, BB Variant (3.5e Variant Rule)
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Armor BB Variant
The d20 combat system infers that armor defends a character by reducing the chance that an attack will deal damage. This does not take into account a reduction of damage from the armor or that the armor itself will become less effective as it is damaged. Combining this system allows for a simple allocation of resources to encompass damaging equipment (without it being annoying), the practicality of actual armor, and D&D mechanics.
Defense Bonus And Damage Reduction
To summarize, a character can have, up to, half of his/her armor AC bonus as DR/Adamantine and his/her shield AC bonus as DR/Adamantine. This should be settled before the armor/shield is created/found, though any enhancements to the AC bonus of armors/shields should allow a potential increase in DR if the player desires. Why wouldn't the player always want more DR? This is because of a secondary mechanic, damaging equipment. Each point in DR adds a 5% chance to hit the armor and a 10% for the shield.
|Table: Armor and Damage Reduction|
|Light armor||Bonus||Damage Reduction|
|Medium armor||Bonus||Damage Reduction|
|Heavy armor||Bonus||Damage Reduction|
|Shield, light wooden||+1||1/Adamantine|
|Shield, light steel||+1||1/Adamantine|
|Shield, heavy wooden||+2||2/Adamantine|
|Shield, heavy steel||+2||2/Adamantine|
As a standard, there should be a base 10% chance of any attack "damaging" an armor (or shield if the player wishes to use it (as using a shield and gaining its AC bonus should also be a choice)) if the attack hits. Upon a successful hit, roll a d100 and if within the hit percentage, act as if the attack also "hit" the armor (with damage equal to the original attack) (NOTE: If the player chooses to use a shield to block an attack (gaining both its AC bonus and DR), the hit d100 is rolled for both armor and the shield (both, either, or neither may be hit)). The hardness of the material of the armor/shield is like DR/- to the damage and anything over the hardness, damages the HP of the armor/shield (again, the same as the material's hit points).
If the Hit Points of the armor are equal to or less than twice its AC bonus, the armor becomes "damaged" and costs twice as much to repair. Additionally, the AC bonus of the armor is maxed out to twice the current HP of the armor (rounded up).
The hardness of the armor/shield is equal to the material's hardness. The HP of armor is equal to the material's HP plus 5 x the AC bonus. A shield's HP is equal to the material bonus plus: Buckler 0, Light wooden shield 2, Heavy wooden shield 10, Light steel shield 5, Heavy steel shield 15, and Tower shield 15.
|Leather or hide||2||5|
|Wood or darkwood||5||10|
|Iron, steel, or deep crystal||10||30|
For example, iron has 30 HP and a hardness of ten. If a full plate of iron is struck by an attack that deals 3 damage, all damage is negated. This is true all the way to 10 damage. At 11 damage, the armor would lose 1 HP. Full plate has an AC bonus of +8 (+40 HP), so say the armor takes 64 points of damage (54 HP damage). The HP of the armor is now 16 and the armor is "damaged." Lose another 2 HP (14 HP) and the AC bonus of the armor is now +7. Only when the armor's HP is 16 or above (through repair) does it regain its full AC bonus (though the armor remains damaged until it is completely repaired).
When an armor/shield is hit (the hit % was rolled and the armor/shield was hit) the player may choose to shift half of the damage. This shifts between the character and the armor shield or the other way around. That is, the armor/shield may take half the damage of an attack for the character or the character may take half the damage from the armor shield. Note the word HALF, as the damage transferred can only be half (rounded down) the attack damage, no more, no less. If both a shield and armor are hit, the character cannot shift all of the damage, only half of a character's damage may be shifted per attack (though the character may take half of both the armor and shield damage). Damage added to an armor/shield is added to the total damage it takes (its hardness cannot reduce damage twice).
For example, a character is hit with 16 damage. His/her iron (hardness 10) armor and shield are also hit with 16 damage. Normally, the armor/shield would reduce 10 damage and lose 6 HP. The character can shift 8 damage from each the armor and/or shield (taking 24 or 30 damage) and have the armor/shield only take 8 damage (reduced to 0 due to hardness). Or, the character can shift 8 damage from themselves (only taking 8 damage) to either the armor or the shield (not both so the character takes 0 damage). The, let's say, armor now takes 24 damage. This is reduced to 14 damage (due to hardness). If the HP of a shield or armor drops to 0 or below, it is destroyed and useless.
Magic Armor and Shields
An enhancement bonus (if any) increases its armor/shield bonus to AC, and may or may not increase the DR at the player's discretion. The formula for AC-to-max DR is 2-1 for armor (rounded down) and 1-1 for shields. A +1 chainmail, for example, can go from DR 2/Adamantine to DR 3/Adamantine; however, when becoming a +2 chainmail it keeps its maximum damage reduction of 3/Adamantine. At +3, the chainmail can become DR 4/Adamantine.
Stacking Damage Reduction
The damage reduction granted by armor stacks with other damage reduction of the same type, but only the same type. A Lvl. 7 barbarian's DR 1/- does not stack with its full plate's DR 4/Adamantine. In this case, the best DR for the situation is chosen (DR 1/- if struck with adamantine).
A creature’s natural armor cannot gain DR unless the player makes his/her natural armor able to be damaged. If this occurs, treat natural armor as regular armor (including the need to repair it).