[Homebrew] Our BX/OSE Combat House Rules

The following hodgepodge is a glimpse at the house rules we use in our Old-School Essentials campaign Portals of Eremus. Some of them were borrowed from other games and supplements, others are my own. Some of them have been already used in previous campaigns, others were first introduced for Eremus. The goal was to spice up B/X combat without making the process too cumbersome. Only time will tell if they succeed at that or not, but so far they worked fine for us - especially the weapon properties!

If you are looking for complicated combat rules, you are in the wrong place.
Check out Player's Option(TM): Combat & Tactics instead.

Death and Dying

At 0 hit points the player character loses consciousness and begin to bleed out, losing 1 hit point per round until healed. Death is instantaneous when the current hit points reach half the character's Constitution score (round up) in negative. E.g. a character with CON 17 dies when reaching -9 hit points.

After regaining consciousness, the wounded character needs a full week of bed rest. Until completely rested the character moves at half the normal rate, cannot carry heavy items, and receives penalties in combat.

Being reduced below 0 hit points leaves the character with a hideous permanent scar.

Disarming

When attempting to disarm a successful hit doesn't cause damage, but forces the defender to make a saving throw versus petrification or lose the weapon being held.

Distance: The weapon falls at the owner’s feet if it is of the same size as the attacker’s weapon, or lands 1d10 feet away if smaller. Recovering the weapon takes a round.

Limits: Weapons held in two hands cannot be disarmed. Disarming can only be used against weapons of the same length or shorter.

Fumbles

When the character misses by 10 or more on a natural 1 roll on the following table to see what happens:

1d20	Result
1-2	Just a minor inconvenience. Laugh it off.
3-4	Weapon slips. -2 to the next attack roll.
5-6	Weapon damaged. -1 to damage rolls until repaired.
7-8	Weapon stuck in something. It takes an attack to free it.
9-10	Weapon dropped or thrown. It lands 1d10 feet away.
11-12	Attacker slips. +2 to the next attack of the enemy.
13-14	Attacker stumbles. Free attack roll for the enemy.
15-16	Attacker falls. It takes a round to regain footing.
17-18	Attack roll against self. Classic.
19-20	Attack roll against nearby ally, or damage self when there is none in reach.

Grappling and Overbearing

When grappling each attacker makes an individual attack roll. Those attackers who hit roll their hit dice totals and compare their sum against the defender's hit dice total roll. E.g. two 1 HD orcs trying to pin a level 3 cleric roll 2d8 versus 3d6.

Attackers have higher total: The defender is pinned and can be executed or knocked out for 1d6 turns next round. Before that defender can try to break free, or another grappler can join the fray to pull the defender out.

Defender has higher total: The attackers are beaten back and stunned for a round.

Draw: No one manages to get the upper hand this round. 

Parrying

When parrying the character’s total melée attack bonus* is added as an Armour Class bonus that round. The bonus is only added against missile weapons if the character has a shield. The parrying character can't attack until next round.

Tripping

When attempting to trip a successful hit doesn't cause damage, but forces the defender to make a saving throw versus petrification or fall prone.

Regain footing: Can be done next round during the movement phase.

Limits: Must use weapons that can hook the victim’s leg. It’s impossible to trip creatures without leg. Creatures with more than two legs gain a +1 bonus to their saving throws per additional leg.

Weapon Properties

Crushing weapons (club, mace, staff, stone, torch, warhammer, etc.) get a +2 bonus to attack rolls against heavy armour (chainmail and above)**, unless the armour is of much harder material. E.g. a wooden club against plate mail does not get any bonus. A natural 20 that hits*** stuns the defender for 1d6 rounds. Another successful strike from a blunt instrument knocks the defender out for 1d6 turns.

Piercing weapons (arrow, bolt, dagger, javelin, lance, polearm, short sword, spear, etc.) impale foes on a natural 19-20 that hits. Impaled creatures suffer a damage roll from the weapon again when they do strenuous activity, or when the weapon is forcefully extracted. If the weapon is held by someone the victim is held at bay until the weapon is removed. Extracting the weapon forcefully costs an attack, while doing it carefully to avoid additional damage requires an entire turn.

Slashing weapons (battle axe, hand axe, polearm, sword, two-handed sword, etc.) can cleave, which allows a free attack against another foe within reach after killing someone. On a natural 20 that hits the weapon causes double damage. If the victim falls to 0 hp the attack tore off a random limb.

Some weapons can be wielded in different ways, changing the damage type. Depending on the weapon this can result in reduced damage, or the weapon handled as another weapon that’s more fitting for the situation - eg. attacking with a spear’s shaft counts as a staff.

* I assume attack bonus and ascending armour class.
** In case of monsters I use the following rule of thumb: hide and fur count as leather, scales count as chain, hard shell count as plate.

*** By this I mean the attack would hit even if the natural 20 wasn't automatic success.