New Defense Rules

 Never really satisfied with the original GURPS rules for handling defense in combat, I've decided to design some new ones, and here they are.

 Basic Principles

  Defense Maneuvers

   There are still three defense maneuvers, and they are treated as such (according to the Maneuvers rules from GURPS Martial arts or Compendium I):

   * Block: This maneuver defaults to the Shield or Buckler skills, modified by the shield size (see below). Cannot be improved.

   * Dodge: Defaults to DX-4. It cannot be improved as a maneuver, but instead a new Physical/Easy skill of the same name can be learned. Note that some Martial Arts styles consider Dodge a very important skill, and it should be included in it as a primary or secondary skill; some examples are the western boxing and some European fencing styles.

   * Parry: This maneuver defaults to the skill with the weapon it is used with, with modifiers depending on the weapon type (see below). Cannot be improved.

   Defense Roll

    When an attacker rolls a successful attack roll, the defender chooses one of his available defenses and roll: if he makes his roll by an amount equal or greater than the one the attacker succeeded by, he has successfully defended.

    Example: The attacker has a skill of 14, and rolls a 11 -- success by three. The defender has to succeed by three or more to defend himself.

    In case of an attack that can be defended against (usually Dodged), but was not aimed directly against the character, such as avalanches or explosions, the GM should apply an appropriate modifier to the character's defense roll.

   Modifiers

    Various modifiers can affect the Defense roll, depending on the Defense Maneuver used and other circumstances.

    All Defense Rolls

     * The character has Combat Reflexes advantage (p. B20): +1 

     * The character is Stunned: -4 

     * The character was wounded in the same or previous turn: minus the amount of damage received 

     * Encumbrance: minus double the Encumbrance penalty

    Blocking

     * Shield size (p. B76): 

       * Large or Force shield: +1 

       * Medium shield: no modifier 

       * Small shield: -1 

       * Buckler: -2 (note: using a buckler with the Shield skill is at -4!) 

     * Improvised shield: -3 to -1 (GM's decision) 

     * Blocking a flail: -4

    Dodging

     * Acrobatic dodge (p. B108): +1 if successful, -2 if failed

     * Dodging an attack from a side hex: -2 

     * Against bare-handed or thrusting attacks: +1/8 his Boxing skill (round down)

    Parrying

     The primary factor affecting the Parry roll is the weapon used for it. Generally, it can be said that a small weapon is harder to parry with, while with very large weapons their size gets into way. We can then divide weapons in several groups, each of which have its own modifiers to Parry roll:

     * Small weapons (knives, jitte etc.): -4 (except when used with Main-Gauche skill) 

     * Polearms (halberds, lances etc.): -3 

     * Fencing weapons (including Main-Gauche): no modifier 

     * Staff (used two-handed): no modifier 

     * Most other weapons: -2 

     * Unarmed Parry (using Brawling, Karate, Judo or Boxing): -1 

     Other modifiers that apply to all Parry rolls: 

     * Parrying against a flail: -4 

     * Parrying an attack from a side hex: -2

    Shields

     Although counted as a separate defense maneuver, Block is actually nothing but a Parry with a shield. Although it's usually used with shields, a character can use anything to block an attack — from a beer mug to a trashcan lid.

     A successful Block usually means that the attack was turned by the shield, which has taken most of the damage intended to the defender, per sidebar on p. B120. However, with these rules, damage to the shield is calculated on any successful Block, no matter how much it was succeeded by.