ARMOUR AS DAMAGE REDUCTION

This is an idea that has floated around d20 games for a long time. A lot of players house rule this kind of thing; its often discussed if armour as damage reduction wouldn’t be a more accurate reflection of the effect armour has; and in the Wizards of the Coast publication Arcana Unearthed it is given as a possible modification. This section deals largely with the change from armour as a defense bonus to armour as damage reduction. The actual ruleset are also repeated in the rules and combat section; though that section lacks an explanation of the differences between the d20 Modern system and this system nor does it justify the logic behind this decision. This section does just that.

 

What’s the difference?

In the d20 Modern game, donning a bulletproof vest; a forced entry unit or some other kind of body armour offers bonus to Defense. In the d20 Warhammer 40,000 game there are plenty of things that can give you a bonus to defense. Psychic deflection bonuses, forcefield bonuses and shield bonuses from storm shields or crusade shields. Armour however does not provide a bonus to Defense. All armour in the d20 40k game add +0 to the player’s defense score.

 

So what does armour do?

Armour gives you a reduction to incoming damage. It may reduce incoming damage to 0 or it may just make you take a percentage of the damage. Damage Reduction is a core part of the d20 Modern System Reference Document; the Tough Hero for instance gets Damage Reduction. The idea of Damage Reduction has changed only slightly.

 

How has Damage Reduction changed?

Warhammer 40,000 has a very definitive Armour Penetration system with each armour providing a special armour saving throw which is negated or not negated based on an Armour Piercing value of the weapon at hand. Damage Reduction has changed to represent this armour piercing system. Any Damage Reduction listed in the game is given with ‘/’ (slash) in the middle. The number before the slash is the DR or Damage Reduction. This is the amount that in the best case scenario you will reduce incoming damage by. The number after the slash is Damage Reduction Threshold. This is the number that determines how good you armour is at maintaining the current level of Damage Reduction. Armours with a low DRT are easier to penetrare and armours with a high DRT are more likely to use a higher percentage of their DR.

 

DR/DRT and DRP

As noted above Damage Reduction / Damage Reduction Threshold is described as part of an armour’s base description. Also important for calculating Damage Reduction is a weapon Damage Reduction Penetration (or DRP). Each weapon in the game has a Damage Reduction Penetration. (See Weapons of the Dark Millenium). If a weapon does not have a listed DRP then it is a DRP 0 attack. These three values are all you need to determine the damage inflicted on a target after the Damage Dice have been rolled.

 

Calculating Damage

The following formula will calculate damage. Though presented as a formula its actually quite simple. Plus for most armours other than natural armours is already calculated for you. In simple terms Damage Reduction is reduced by the ratio of DRP to DRT. The formula is:

 

Damage Inflicted = Damage Rolled – DR * ( DRP – [DRP / DRT] )

 

Damage always favours the defender and always rounds down. Damage Reduction never increases the damage so if a negative number results treat the damage rolled as damage inflicted (no reduction).

 

Example 1:

A falchion deals 2d4 damage (5 on average). It has a DRP of 0.

A bulletproof vest has a DR/DRT of 4/+1.

 

Damage Roll = 5, DR = 4, DRP = 0, DRT = 1.

 

5 – [4 – 4 * (0 / 1)] = 5 – (4 – 0) = 5 – 4 = 1

 

On average a falchion deals 1 point of damage to a target equipping a bulletproof vest. This example shows, a DRP 0 weapon causes the full damage reduction to apply.

 

Example 2:

A Boltgun deals 2d10 points of damage (on average 11). It has a DRP of 2.

Full Flak Armour has a DR/DRT of 8/+2.

 

Damage Roll = 11, DR = 8, DRP = 2, DRT =2.

 

11 – [8 – 8 * (2 / 2)] = 11 – (8 – 8) = 11 – 0 = 11

 

On average a boltgun deals 11 damage to a target in flak armour. This example shows, a weapon that has a Damage Reduction Penetration (DRP) that is equal to or greater than an armour’s Damage Reduction Threshold (DRT) reduces the armour’s effective Damage Reduction (DR) to 0.

 

Example 3:

A Boltgun deals 2d10 points of damage (on average 11). It has a DRP of 2.

Light Carapace Armour has a DR/DRT of 10/+3.

 

Damage Roll = 11, DR = 10, DRP = 2, DRT =3.

 

11 – [10 – 10 * (2 / 3)] = 11 – (10 – 6.67) = 11 – 3.33 = 7.67 = 7

 

On average a boltgun deals only 7 damage to a target in Carpace Armour. This is an example of damage reduction that is partly reduced by a high DRP weapon. Specifically the DR of 10 is reduced by 2/3 of its original value to 3 and a third.