Laws of Combat
No matter where you go, no matter what campaign setting you go to, no matter who you speak to who has played AD&D, there will be someone who thinks they could do better. This rule is too easy on the players, still this one is to tough, and I don't quite get what this one over here means. Every DM - and thus, every campaign - has its own rules variations, and these are mine:

This page deals with anything I couldn't put on another page. They all involve dice rolling, decision making, or combat in some way or another, including (even more) rules on armour, poison, and backstabbing/throat slitting. My players want me to stay away from energy draining, but I might try my hand at that sometime soon. :0)

 Poison
Backstabbery
Armour

Poison:
When a character's life comes down to the roll of a single die. This 'die' or die method seems a little harsh, so I have come up with an alternate method. When attacked with a weapon that has been coated in poison (or injects it, like a giant scorpion's sting), the saving throw vs. spell is not immediately rolled.
The first step is to roll for damage, with normal bonuses and penalties. Once damage has been dealt, the same amount and types of dice (with the same modifiers) are rolled again to see if the poison makes it into the victim's blood stream. If the roll comes up with less than the amount of damage dealt, the poison has successfully entered the victim's blood.
At this point, the victim then rolls a saving throw vs. poison, and is affected as usual.
Within the turn, the victim becomes weak (-4 to Str, Dex, Con), and must have one day of bed rest before returning to full strength.
For example, Edge, a 7th level fighter has just been stabbed by a giant scorpion he had been trying to tame. The stinger deals 2d6 damage, and the DM rolls a four and a five. Edge takes nine points of damage, and has a very good chance of being injected with poison. The poison check comes up with an eight, just enough to inject edge with type D poison. Edge fails his save, and takes 30 extra points of damage. He collapses in a heap as his body tries to battle the toxin. His friends chase the scorpion off and take Edge back to camp. The next day he is well rested, and ready to continue.



Backstabbing:
The AD&D Players Guide states that a successful backstabbing attempt will deal from two to five times as much damage as a normal attack. A typical backstabbing would go something like this:

Theros Swiftfoot, Master Theif, slinks along the wall of a building. Shivering in the cold, Theros pulls his cloak tighter and looks at the spires of the museum that rise high into the crisp night.
Rounding a corner, he spots a man in armour guarding the entrance, his back turned. Theros successfully Moves Silently and approaches the man from behind.
Gerald Thirris, a 7th level Fighter, is bored, cold, and afraid some halfling thief is going to think too much of himself and get him right in between the ribs. He doesn't know why he volunteered to guard the museum, but the job pays well. He does have 46 hit points, after all.
Theros draws his dagger, and successfully backstabs the man. As a 8th level thief, Theros' backstabbing deals 3x the amount of damage a normal attack would. Theros rolls for damage (a dagger does 1d4), and comes up with 2.
Gerald laughes under his breath. 6 points of damage. He draws his sword, and makes short work of the halfling.

With a quick modification, backstabbing, throat slitting, impalements, and all those other nasty things that should deal alot more damage much more realistic.
When a thief successfully backstabs, multiply the damage multiplyer by the maximum amount of damage the weapon deals. For example, a dagger would deal 12 points of damage in the previous example. It would also open a wound that would bleed for the same amount of damage each round, diminishing by two for each passing round. Also, at the end of each round, the victim makes a save vs. death (with camulative penalty of -2 per round) or pass out due to loss of blood.
Lets try that example again, with the new rules.

Theros Swiftsoof, Master Theif, slinks along the wall of a building. Shivering in the cold, Theros pulls his cloak tighter and looks at the spires of the museum that rise high into the crisp night.
Rounding a corner, he spots a man in armour guarding the entrance, his back turned. Theros successfully Moves Silently and approaches the man from behind.
Gerald Thirris, a 7th level Fighter, is bored, cold, and afraid some halfling thief is going to think too much of himself and get him right in between the ribs. He doesn't know why he volunteered to guard the museum, but the job pays well. He does have 46 hit points, after all.
Theros draws his dagger, and successfully backstabs the man. As a 8th level thief, Theros' backstabbing deals 3x the amount of damage a normal attack would. Immediately deals 12 points of damage.
Gerald curses under his breath. 12 points of damage! He collapses to the ground, trying to stem the blood flow. The next round, he takes 10 points, and fails his save. Just before he loses conciousness, he sees a diminutive fellow stoll by, wave, and walk into the museum.

Dont worry, everyone. I know what you're thinking... Does the poor guy make it?
The answer is yes, Theros does escape with a small fortune from the museum.


Armour:
Many DM's out there seem to have their own versions of the armour rule. The two most common seem to be reducing the character's chances of getting hit (the same or variations of the rules seen in the Dungeon Master's Guide and Player's Handbook), or increasing the characters hitpoints or somehow reducing damage. Both of these methods are fine, but there is a third alternative.
Consider briefly a knight clad in plate mail and hit with a sword. The sword is not repelled by some magical force, missing the target, nor does the armour absorb all of the energy of the blow (causing many DMs to favour the 'absorb damage' rule over the 'harder to hit' rule). These rules, however, state that the plate may have indeed suffered damage from the blow, and therefore, the fighter underneath it. Also, while fifty pounds of steel may seem like a lot (especially to the knight wearing it day-in, day-out), it just isn't enough to generate the magnetic field required to cause a sword to miss :0)
What did the armour do then? It stopped the warrior from suffering a greivous wound (a critical hit), and instead suffers a flesh wound (the d8 of normal, statistical damage). The armour prevented a critical hit he may have suffered had he been less equipped.

Armour in this system does two things: Makes the opponent harder to hit, and protects him/her from serious injuries caused by critical hits. Each armour has three aspects: a critical modifier, which affects the odds of being critically hit, an intensity modifier which represents how much the wearer is protected from a given critcal hit, and AC modifier, which makes the character harder to hit.

Critical Modifier: According to Players Option: Combat and Tactics, a character need roll an 18 or above to cause a critical hit (and 3 or less to critically miss). This 'improved' upon the Core Rules design of a 20 to critically hit or 1 to critically miss to make combat more varied and exciting. The critical modifier of an armour is applied to this base of 18. When an opponent makes an attack roll, the critical modifier is added to the roll on a d20. If the modified result is higher than 18, the hit is critical. This keeps with the tradition that a negative armour modifier is good, and a positive modifier being bad.
Intensity Modifier: The intensity modifier is added to (or subtracted from) the critical hit table to determine the severity of the hit. Once again, a negative number is beneficial to the target.
AC: There is no change in these rules, but AC modifiers are posted for completion's sake.
The armours, and their statistics, follow:
Armour Name
Critical
Modifier
Intensity
Modifier
ACNotes
Unarmoured +6*+20*None
Leather Armour +4*+2-2*None
Light Scale Mail +30-3*

Studs may aid injury

Ring Mail +30
Studded Leather Armour+3*+1
Metal Lamellar +30
Brigandine +30-4*
Worst protection at this AC
Best protection at this AC
Hide +4+1
Scale Mail +20
Chain Mail +20-5*None
Improved Chain Mail +20-6*
Criticals less common but more dangerous
Criticals more common but less dangerous
Splint Mail +1+1
Banded Mail +20
Plate Mail +0-1-7None
Field Plate Mail +0-1-8None
Full Plate Mail +0-1-9None
Channeller Mantle +4*+2-2*See rules below
* Include Defensive Adjustment for High Dexterity/Balance


Critical Augmentation:
A character with critical augmentation gains a +2 to Critical Modification.

Mantles:
Wizards may also modify their mantles to take advantage of these rules. The chart below shows how.
Modifies:Type of ThanumCost per modification
Critical ModifierEarth or Fire-1 per thanum (max 4)
Intensity ModifierAnimal, Earth or Plant-1 per 2 thanums (max 4)
Armour ClassEarth or Wind-1 per thanum (max 10)
Resist SurgingFire or Water5 thanums

An unmodified mantle functions as leather armour unless it is augmented. A mantle affords a +4 Critical Modifier (enabling a critical hit on a 16 or greater) and increasing the critical hit intensity by 2. Armour class is reduced by 2.
Also, when a wizard is successfully critically hit, his mantle 'surges' to stay intact. When hit critically, the channeller must make an additional saving throw for the mantle. If it succeeds, the mantle remains intact and the channeller is automatically "Moderately" fatigued if he was not so already (unless this would reduce fatigue, in which case there is no effect). If the save fails, the mantle collapses after the critical hit (it can still affect intensity) before dissipating. If the Resist Surging ability is chosen, this paragraph can be ignored.

This is a rather pathetic mantle, so let us take two examples to 'beef it up'.

Derak is a 7th level channeller who wants his mantle to focus on improving his armour class. He expends 5 of his 7 possible thanums into armour class, and the remaining two into Critical Modification. He is now armour class 3 (8 minus the 5 put into AC), and can be critically hit on a 18 or greater (base 16 + the 2 spent on Critical Modification). His mantle is now comparable to banded mail. However, if he IS critically hit, it will be more gruesome than it would have been had a fighter in banded mail suffered the same injury.

Kazorith is a 20th level channeller! He expends ten of his twenty possible thanums into armour class, all four possible into the Intensity Modifier, and three more into Critical Modification. He uses the five additional points to proof his armour against surging. He is now armour class -2 (8 minus the 10 put into AC), and can be critically hit only on a 19 or 20 (base 16 + the 3 spent on Critical Modification). His mantle protects him from excessive injury caused by critical wounds (but cannot actually absorb punishment like true armour).

More mantle abilities will be in the next update!