This combat expansion is for use with my combat system already presented, but can also be applied alone, with no difficulty. There are a few terms this new expansion uses which I shall define below: Armor Value(AV), Armor Piercing(AP) Attack, Armor Reducing(AR), Dexterity/AC and Initiative(D/AC/I) Penalty and Toughness.
Armor Value or AV is the amount of damage a suit or natural armor absorbs from a successful attack. Armor and all magic plusses on it, in addition to all magic that simulates armor does not improve AC, but bestows an AV instead. All armors give a base AV equal to 10 minus the original AD&D AC it would have given. For monsters with a natural AC, the DM must decide how much of that AC comes from armor/toughness and how much from speed, size or dexterity. Only that derived from armor/toughness counts. The rest of the monsters AC counts as its Defense Pool(see my combat rules for details). If you do not use my combat system, then it counts as the creatures base AC. So an AC 5 ogre gets all of its AC from armor/toughness, it has an AV of 5.
A hard and fast way to figure out the amount of AC to apply to each area is by considering both the size, and the speed of the creature. Smaller creatures get some AC from their small size. Every size below man-sized, give them 1 point from their AD&D AC toward their base AC(DP if using my system). Also, speed helps, so for every 3 points of ground movement rate above 12 for bipeds, give them 1 point from their AD&D AC toward their base AC(DP for my system). Quadrupeds get 1 point towards the AC/Dodge aspect for every 6 points of movement over 18.
A gargantuan dragon with AD&D AC of -3 would have all its AD&D AC as armor, being neither small, nor fast. Thus, he has a Defense Pool of 0 points(see my combat rules) or a base AC of 10 if you do not use my combat rules. The rest of his AD&D AC is armor, so his AV from armor is 13. However, he is gargantuan, which gives him a toughness of 4(see toughness below), that is additional to his AV. Thus, his full AV is 13, with 4 extra points of toughness. Dragons suddenly become very tough. Most attacks just bounce off its hide and bulk, making these beasts very dangerous for all but the most powerful heroes. Hope they can find a weak spot in his armor, or try to make head shots if possible(see below).
Slashing/Piercing/Blunt Attacks are the 3 basic categories attacks fall into. There is 1 other I will discuss later, but it is a special attack form. Base AV applies in full against Slashing attacks and against most Piercing attacks as well. Some piercing attacks are called AP(armor piercing) attacks, which halve armor resisting them, but this is discussed later. AV against Blunt attacks acts in a special way. Only half(rounded down) of the base AV applies normally, the rest of the AV only cushions the blow, and all damage it would normally have absorbed gets partially through, as temporary or stun damage(the same damage unarmed combat inflicts), thus this part of the armor acts just as toughness does. Toughness is not halved in this way, but applies in full. Toughness basically serves to re-enforce armor against blunt attacks or attacks that have AR bonuses(detailed later), and can be seen to simply restore any AV that these blunt or AR attacks reduce to cushion effect only. So a creature with a 2 toughness, could ignore up to 2 points of AV reduction from blunt/AR attacks. Any left over toughness acts as normal, reducing damage it absorbs to stun. Stun damage is treated just like regular stun/temporary damage from unarmed combat, every 4 points of it means 1 point was real(but see toughness below). Recovery of this stun damage is just as that for normal unarmed combat damage, but I suggest this method: Each round of rest(no strenuous activity or combat, not even self-defense) allows recovery of 1 point of such damage. If the individual cannot rest, he must pass a save vs. death(or Endurance check) each round, and if he passes it, he recovers 1 point, otherwise he recovers no damage.
Constriction/Hug/Crush Attacks are a 4th and special type of attack I mentioned above. Armor is not as resistant against this type of attack, so the Base AV is halved(round down) against such attacks. Some attacks get this classification even if not specifically a hug/squeeze/or crush attack. Any attack 2 or more sizes greater than the defender which is either a claw(grab/snatch) or bite attack counts as this type of attack form, halving the armor resisting it.
Armor Piercing Attacks also know as AP attacks are special attacks that are designed to penetrate armor via a very narrow point. All AP attacks halve(round down) any armor or toughness resisting them. These attacks typically do less damage than a similar attack that is not AP. All picks are AP weapons. Bodkin arrows(known as pile arrows in some books) get this AP bonus. All spears/pikes set to receive a charge are classified as AP attacks for that attack mode only, in addition to the fact that they do double of what damage gets through the armor. Lance charges are as above for spears/pikes. Any piercing weapon with a narrow point would fall into this area.
Armor Reducing Bonuses are similar to AP attacks in that they get bonuses against armor. They do not halve armor as an AP attack does, but reduce its AV by a specific amount. All 2 handed weapons have an AR bonus of 1 for example, as their extra momentum helps them get through armor a bit better. So when using a 2 handed weapon, reduce the AV resisting you by 1 point. Weapons that are designed for 1 or 2 hand use get a +1 to damage and +1 AR above the damage they do 1 handed when used 2 handed. Other weapons not designed for 2 hand use, get only a +1 damage bonus when used 2 handed. This AV reduction effect does not totally negate the AV is reduces, but reduces it to only a cushion effect, turning damage it absorbs into stun, rather than negating it as usual.
Large attacks also get an AR bonus as the mass of such attacks can pound through armor more effectively. Large attacks get an AR of 1, in addition to any other they might enjoy. Huge attacks get an AR of 2, and gargantuan attacks an AR of 4. Every 25 a creature is over the base 25 to qualify as gargantuan, places it 1 step above gargantuan(call it what you will). Each extra step over gargantuan adds 2 to the AR of 4 gargantuan creatures already get.
AR bonuses do reduce the AV of the armor resisting them, but these reduced AV points are not totally ignored, instead, the reduced AV points only reduce the shock of the attack, rather than absorbing the damage altogether. These reduced points still absorb damage, but all such damage they absorb is not negated but reduced to temporary/stun damage instead.
For example, a man in full plate has an AV of 9 against slashing attacks. If attacked by a 2-handed sword, which does d10 and has a 1 AR bonus, his AV is reduced to 8, with the 1 reduced point acting only to reduce the shock of a blow. If hit for 10 points of damage, 8 are absorbed and negated, 1 is reduced to stun damage and the last gets through as 1 point of real damage.
Dexterity/AC and Initiative Penalty or shortened to D/AC/I penalty is applied when armor is worn by an individual. Each suit hinders the wearer by some amount, which applies to penalize his base AC, reduce his dexterity checks(not the score itself) and penalize initiative rolls by the stated amount. The penalty is listed in the Fighters Handbook, but a quick rule to use is 1/2 of the base AV(rounded up) of the armor, minus 1. Thus AV 2 has no penalty, AV 3-4 has a 1 point penalty, AV 5-6 a 2 point penalty, AV 7-8 a 3 point penalty and AV 9 a 4 point penalty. Field and full plate are special in that they are well balanced and should have their penalty reduced by 1. So field plate(AV 8) has a 2 point penalty, while full plate(AV 9) has a 3 point penalty.
Armor proficiency in an armor reduces this penalty 1 point. Also, magic armor reduces the penalty 1 point more(regardless of the actual plus).
Thus, a base AC 10 warrior who is not proficient in his plate mail(non-magical) would suffer a 3 point D/AC/I penalty, so his base AC would be 13(yep, that is correct), he would suffer -3 to all dexterity checks(but he still gets his DEX bonus if any, the AC penalty already takes the universal hindrance of armor into account) and he would penalize all initiative rolls by 3. However, his AV would be 7.
Toughness is the final aspect of the armor system. It measures how hard it is to harm creatures who are massive and tough. This toughness value adds to any existing AV the creature might have, acting as "extra" cushion in a sense. Toughness does not negate damage like armor, but reduces it to stun. Stun damage is totally negated by toughness, up to the toughness value, of course. Large creatures have a base toughness of 1, huge creatures have a toughness of 2 and gargantuan creatures a toughness of 4. Each step over gargantuan(see armor reducing above) adds 2 to the toughness of the creature. Those very strong(and thus, densely muscled) for their size(usually only applies to man-sized creatures) also get a toughness value. Take half(rounded down) of their strength bonus to hit, and this is their toughness value. This must be their real strength, magic girdles and spells do not count for this.
Toughness and Stun: normally, every 4th point of stun is treated as 1 point of real damage instead, just as in AD&D temporary damage. But toughness adds to this ratio, so it takes 4 plus the toughness value of stun points to count 1 of them as real. Thus, a monster with 2 toughness must suffer 6 stun to have 1 point count as real against it.
It is easy to convert AD&D armor into AV with the 10-AC rule. However, certain armors have weaknesses or strengths against certain types of attacks.
Leather/Hide/Padded/Ring Mail/Scale/Cord: these armor types have 1 point less AV against piercing attacks.
Chain Mail/Improved Mail: these types are 1 AV point less effective against both piercing and blunt attacks, but gain a +1 AV bonus against slashing attacks.
Field Plate: this armor gets a 1 point bonus to its AV against piercing attacks.
Full Plate: this armor gets a 2 point AV bonus against piercing attacks.
Area Effect Damage/Magic Damage and Armor/Toughness
The base AV of armor does help reduce damage taken from area effect damaging spells/weapons that cause physical damage. The base AV absorbs its value in such damage, and this damage is treated separately. Only half of this absorbed damage gets through if the wearer failed its save, and even then only as stun damage, otherwise, none of it gets through if the wearer made its save. The rest of the damage not absorbed in this fashion has the usual effect. If the attack does not allow a save, then only half of the absorbed damage gets through, again as stun, as if the wearer failed its save. Toughness, however, fully absorbs any damage it blocks, regardless of save, reducing this damage to stun, or totally negating its value in stun damage that got through.
For example, Thor is wearing full plate(AV 9) and has a toughness rating of 1 from his 18/00 strength. He is hit by a fireball for 35 points of damage. 9 would be absorbed by the armor and 1 point reduced to stun by his toughness, the other 25 having the usual effect on Thor. Now, if Thor made his save, those 9 points absorbed by the armor would be totally negated, and the 1 point would be reduced to stun by toughness, so Thor would take damage only from the 25 that passed his armor, and because he saved, he would take 13 points real, and the 1 point of stun. If he failed to save, he ends up taking half the damage his armor absorbed in stun, or 5 points. The toughness point still works damage normally, as it does so regardless of saves. In this case, the toughness point would totally negate 1 of the 5 points of stun that got through, so, in addition to the 25 that got past his armor and toughness, he would take 4 points of stun.
Certain attacks are inherently armor ignoring in nature. They slip through even the slightest opening and find their mark. Magic missile type attacks are in this category. AV does not affect magic missile type attacks. However, toughness does absorb such attacks, reducing damage to stun. Thus, magic missile spells prove less effective against such giant beasts as dragons for the most part, as each missile must get through 4 toughness points, merely stunning the beast!
Again, Thor is wearing his full plate armor, and has his toughness of 1. He is hit by a magic missile spell which fires 5 missiles at him, each doing, say, 4 points of damage. His armor is ignored, but his toughness reduces the damage of each missile by 1 point, reducing it to stun, so he takes 3 real points per missile, or 15 points, and 1 stun per missile, or 5 stun. Lance of Disruption is a better spell to hit Thor with, as it both ignores armor, like magic missile, and does more damage. If hit by it for, say, 30 points, only 1 point is reduced by toughness, so Thor takes 29 real and 1 stun, or 15 real and 1 stun should he save for half.
Special Notes: DMs can allow called shots to exploit weak spots in armor, if you deem such spots even exist. And the rules that allow partial armors also allow called shots to bypass armor and hit exposed areas. Head shots(-8 to hit) are generally very effective in "stunning" foes, and such attacks give the strike a +2 AR bonus, and a +2 to knockdown rolls.
Critical Hits will now tend to be easier to score, as the AC of foes will usually be less than AD&D. However, when applying critical results, only double/triple damage that actually gets through armor. If no damage gets though, no critical is scored, and no special effect can occur.
A few examples are provided here to help get these ideas across. A man in chain mail will have a base AV of 5, with AV 3 against piercing and blunt attacks. Thus, against blunt attacks, it will be AV 1, with 2 points to reduce damage to stun level. Against slashing, it is AV 5 and against AP attacks, it is AV 1. A bodkin arrow does d6 and is AP. Thus, it does d6-1 to the man if it hits. I personally limit true longbows to 14 strength minimum and have them do d8+1 with broadheads, and d6+1 with bodkins. Crossbows are also AP weapons, but get none of the other bonuses the Player Option book says. Against a d8+1 heavy crossbow, which is AP, the man takes d8. If hit with a mace, for d6, say it does average damage, or 4 points, his armor blocks 1 and reduces another 2 to stun damage. The last point gets through as real. Thus, he takes 1 real point and 2 stun points.
Same man hit by a 2 handed sword. It does a d10, and has a +1 AR bonus. Thus, the usual AV of 5 is now an AV of 4 against the sword, with 1 point as shock absorbing resistance. If the sword did 8 points, 4 are blocked, 1 reduced to stun, and 3 get through. So the man takes 3 real and 1 stun point of damage. Had the same blow hit him in the head/vitals, the attack would get a +2 AR, furthermore, the +1 AR the sword has already makes this a +3 AR total. This reduces the AV 5 to AV 2, with 3 points of "toughness" essentially, since the reduced points go to shock absorbing defense. So it has 2 points blocked, 3 reduced to stun and 3 that get through. Thus, the blow does 3 real and 3 stun points.