Critical Hits & Fumbles
In rolling a 20-sided die to hit, there are certain natural results (the actual number appearing on the die) that will cause either a 'critical hit,' 'friendly fire' or a 'fumble' in my combat system. Each of these is explained below:
20 Critical Upon rolling a natural 20, the combatant has achieved a critical hit; this means that the amount of damage normally done by the combatant's weapon (or other natural attack associated with 'to hit' rolls) will be, at minimum, doubled. Having rolled a 20 on a d20, the combatant should then roll the die again. If another 20 is rolled, the damage of that attack will be tripled and the die rolled again. A third natural 20 will cause damage to be quadrupled; the fourth natural 20 will cause damage to be quintupled; and so on. The possibility of increasing damage ends when a roll of other than 20 occurs.
If the roll following a natural 20 critical hit (however the number of 20s rolled) is a natural 19; and if the opponent is not wearing a helmet or has its head unusually armored; then the damage is treated as another increase in multiplication without rolling another d20.
For example, a combatant using a long sword swings at an attacking hippogriff and rolls a 20. The combatant then rolls the d20 again and rolls a 19. The damage against the hippogriff is treated as triple because the hippogriff is an animal that does not possess an armored head. The attacker rolls damage; the fighter then adds any bonus to damage resulting from strength, spell or weapon; this total is then tripled. Therefore, if the attacker were a fighter with a 17 strength, using a +1 weapon, while affected by a prayer spell, rolling a 4 on a d8, then the total damage done would be (4+1+1+1) x 3, or 21.
Note that if a combatant requires better than a natural 18 to hit an opponent, a natural 20 is NOT considered to be a critical roll.
Friendly Fire If a combatant is hurling or firing a missile weapon, then a natural 2 on the attack die has a chance of indicating that a friendly fire incident has occurred and that the attacking combatant has hit an associate of the attacker.
Friendly fire can only occur if there is an associate that is, first, either 15º to the left or right of the target; and second, no more than 7 hexes beyond the target. This means that a friendly fire can occur if the associate is nearer to the attacker, regardless of distance.
If no associate conforms to these location rules, then friendly fire has not occurred and the natural 2 is ignored.
Note that armor class has absolutely no relevance where determining if friendly fire has occurred.
Damage done from friendly fire equals the normal amount of damage that would accrue from the missile attack, plus any bonuses to that damage. However, in the case of prayer, chant or martial music, both the attacker and the defender receive equal benefits; so no damage from friendly fire is increased or decreased from those effects.
Note that some weapons require a lot of space in order for them to be used, such as mauls, two handed swords, flails, morning stars and pole arms. If used in tight quarters, where the ceiling is less than 8 feet in height or the space of the room is hampered with furniture or other clutter, then a combatant using these weapons can also cause 'friendly hits' with a natural 2. In such cases, normal damage is done to a random adjacent opponent - if one exists.
Fumbles If an attacking combatant rolls a natural 1 on the attack die, then a number of effects are considered to occur associated with the combatant 'fumbling' their weapon.
First and foremost, the weapon is dropped. If this occurs on a stone surface or a tiled floor, then the combatant must roll to see if the weapon breaks. Different weapons break according to different die rolls. If a '1' is rolled in determining the break, then the weapons is considered broken and can no longer be used. Weapons that fall on dirt, wood or other soft surfaces do not need to roll to break.
If the weapon is magical, then two dice of the type indicated by the weapon should be rolled. For example, a short sword breaks on a 1 in 6; a magical short sword should then roll 2d6. If a '1' occurs on both dice (snake eyes) then the magical weapon is downgraded by 1 degree of magical bonus or possibly broken. If snake eyes were rolled on a +1 short sword, then the sword would break and the magic would be permanently lost. If snake eyes were rolled on a +2 short sword, then the bonus would be reduced to +1 and the sword would remain whole and usable. If the sword in question were +1, +4 vs. reptiles, then the short sword would no longer provide a bonus against anything but reptiles and the bonus against reptiles would now equal +3; otherwise, the short sword would continue to remain whole and usable.
After it is determined if the weapon breaks, the location of the weapon must be determined. This is done with a d8. A roll of 1-2 will indicate that the weapon has fallen at the feet of the owner and can therefore be scooped up again the following round (provided that the owner is then not driven off that hex by an opponent's attack). Rolls of 3 to 8 will indicate that the weapon has landed in a hex adjacent to the owner's hex: left, right or above, as shown on the right-hand figure. If the hex is occupied by an associate, then the weapon can be 'kicked' back to its owner; otherwise, the owner must enter the other hex to retrieve it. Of course, the owner can choose to draw another weapon and leave the dropped weapon on the floor.
If the hex where the weapon is determined to fall into is occupied by a solid object (a building or stone wall, for example), then presume the weapon has rebounded back into the owner's hex. The hex where the weapon is determined to fall may be unusual, such as open air next to a cliff, water, swamp or other surface that makes the weapon difficult to retrieve. The DM should then judge best how to handle the location or possible loss of the weapon (off a ship into the ocean, into a crevice of unknown depth, into a mud pool where the weapon can't be seen but must be felt for and so on). Whether the combatant can find the weapon or not in these situations must be determined according to the situation.
Special Note regarding Thrown Weapons: If a weapon is thrown across a surface that is either stone or hard tile, then the weapon should be treated as a 'fumble' if the attack fails to succeed. A failed attack assumes the weapon has hit the stone/tile surface and must then roll to see if it breaks. A successful hit indicates that the weapon has deflected off the enemy and is therefore presumed to be unbroken.
See Also,
Attacking in Combat
Using Found Objects as Weapons