Today I'm going to look at the effect on needed defenses if you're using the modified Feint and Deceptive Attack rules linked in the series earlier, and with an eye on defenses in the skill range discussed yesterday. For the other parts of this series, click here:
Part III and Part III Adendum
How high of a defense?
Defenses are based on either a skill - Block and Parry - or on Speed minus Encumbrance level - Dodge. Dodge is going to be what Dodge is going to be - it's the best defense (until you critically fail it) but the hardest to directly improve.
A normal man of Speed 5 will have Dodge 8, 11 with Retreat. A melee-focused PC may have more like a Speed 6 or 7, but rarely a Dodge of higher than a 10 before DB, 13 with Retreat. It will not vary that much, and is very vulnerable to Feint if not coupled with a high combat skill.
How how of a skill?
Base skill determines just how much of a Parry or Block the defender will get. We'll shorten up to "Parry" and I'll note the peculiarities of Block below.
Skill 12 means a base 9 Parry
Skill 16 means a base 11 Parry
Skill 20 means a base 13 Parry
Skill 24 means a base 15 Parry
Skill 30 means a base 18 Parry
Like almost any other success roll in GURPS, you're going to ideally have a 16 (3-6 critical, 17 fails, 18 critically fails) or higher. Dropping to 15 (3-5 critical, 16 fails, 17-18 critically fails) comes with a significantly higher chance of critical failure.
But trying to arrange defenses to a 16 in the face of a Feint (-4) and Very Deceptive Attack (-4) is tough. That's a 24 Parry or Block, which means Skill 30 plus Enhanced Defenses 3 (+3), Combat Reflexes (+1), and DB 2. Or a more reasonable skill 24 plus Combat Reflexes 1 and DB 8. It's a question who is inflicting -4 on you from Feint to get there, too, if you're rolling against a 24-30 skill. It's probably more reasonable to assume a -2 to -4 from the attacker.
I think actually makes sense to see defenses at 16 without penalties as a more reasonable aim. That's Skill 18, Combat Reflexes (+1), and 3 DB. That's reasonably doable for a front line fighter even in a non-cinematic game. And it means that choosing Telepgrahic Attack has a real cost (it means skill 14 is sufficient, skill 12 with Retreat) and Deceptive Attack has a real benefit (reduces defenses to a 14 or a 12, depending on the penalty you can absorb and still hit.)
How about bonuses?
+2 Acrobatic Dodge
+1 to +3 Defending Weapon
+1* Balanced Weapon (* gives +1 to skill, which may give +1 to Parry or Block)
+2 All-Out Defense (Increased Defense)
+1 or +3 Retreat
How about penalties?
The biggest fixed a foe can inflict on you is -8. That's a Feint, followed by a Very Deceptive Attack. (Certain things change this, such as custom defense-reducing attacks or the Botte Segrette (Dungeon Fantasy 11, p. 34), can inflict higher penalties, but probably should amount to real threat to defenses.)
Unfixed penalties can result from a "Spinning" attack; equally, so can bonuses. As noted in Part I, you can also change these to a fixed level of -2 and +2 (or -4 and +4).
Situational penalties can make it worse - but like the discussion of situational penalties in Offense, I think it's a mistake to try to allow for fully absorbing such penalties. You should always have a way to be worse off - it gets silly if you defend as well standing up, alert, and facing your target as you do kneeling, stunned, and flanked because your defenses are high enough to ignore those -8 in penalties. This thought process is the same as the one in Part I - Offense, that "maximum" needs to be without situational penalties that you generally do not choose to take upon yourself.
-4 Parry / -2 Block against a flail (-2/-1 versus short-chain flail weapons)
-1 Bad Footing
-4 Can't see attacker
-1 on fire
-encumbrance (for certain Parries, all Dodges)
-2 flank/runaround attack
-1/-2 for height (DFRPG simplified relative height)
-1 two-weapon attack
Multiple Defenses add a wrinkle - Multiple parries are at -4 for each after the first. It's -2 for Fencing weapons (or certain two-handed weapons with Martial Arts.) It's -2 and -1 with Weapon Master. Many cinematic fencers will fight with a "case" of identical weapons, because that gives a -1 cumulative parry penalty off of two identical parry scores. Add in +3 for Retreat, and if they can parry the attacking weapon, they can generally parry it multiple times before their defenses are really reduced or compromised.
Shields warrant a special note. First, Block is identical to Parry for the same level of Shield. It will always come with a Defense Bonus, as you can't use it without equipment. So +1 to all of those numbers, at least.
Second, their multiple-defense cascade either doesn't exist (one Block per turn, per Basic Set), or is -5 (-3, or -2.5 rounded up with Weapon Master) per use with Martial Arts. So it's always worse for multiple defenses than Parry. However, it's a better defense overall.
That said, the rules should apply here just as elsewhere. Block is balanced against Parry well enough in GURPS, and has been since the early days (but not in Man-to-Man, where it bit fairly hard.)
Overall: It's interesting that with sufficient defense additions and situational modifiers, you can raise your Block or Parry to equal or exceed your skill. The fixed Feint and Deceptive Attack rules limit the amount of supression of defenses you can suffer, but to be fair it's never been something high-skill defenses actually suffer very often. It's more limiting the damage to the low-skill defender. At a glance, then, it seems workable and might actually increase the survival chances of the weakest of combatants, but also limit the need to push defenses up to very high levels for fear of Deceptive Attack levels that simply aren't included in the system (except from very special situations and attacks.)