Active defenses as modifiers

[Varyon]

Originally Posted by benz72

Maybe making the calculation is quicker, but it isn't obvious to me on the face of it. How long does it take to recalculate the modifier vs. how long to make the additional roll?
If speed is the issue, replacing 2 second task A with 2+ second task B might not have the desired effect.
If it is indeed quicker, how much time did you save?

I'd imagine you'd just write what your Defense Modifier is on your sheet ahead of time, then when someone attacks you just see if their MoS was enough to soak the penalty. So if you have Block 15, Parry 12, and Dodge 9, you just note that you impose a -5 to hit with a Block, -4 with a Parry, and -3 with a Dodge.

But the proposed system gives radically different hit probabilities compared to RAW. Assuming equal skill and further assuming no bonuses (Combat Reflexes, shields, etc), you're typically looking at around a 45% chance of successfully hitting the foe (succeed on attack, fail on defense) if you're using Deceptive Attack (or even Telegraphic Attack at low skill) to get your skill to around 13-14, which generally gives the highest overall hit probability. With the proposed system, you need to look at multiples of 6 (when the defense bonus changes). At skill 12, that's Parry 9 and thus -3 to hit; that gives a 37.5% chance of actually hitting, which may be close enough to 45% to work alright. But at skill 18, Parry 12 gives only a -4 to attack; that gives a 91% chance of actually hitting. At skill 24, Parry 15 gives a -5; you're at the cap of ~98% chance of actually hitting, and any higher skill is above that. Looking at the in-betweens, skill 13 gives an overall hit probability of 50% (close enough to 45%), 14 is 62.5% (too high from here on), 15 is 74%, 16 is 84%, 17 and 18 are each 91%, 19 is 95%, and 20+ are all 98%.

EDIT: An alternative option that may come closer to the RAW distribution would be to subtract your skill (or 2xBasic Speed for Dodge) from 10 to determine the penalty (which will mean a bonus against those with skill below 10, but that kinda represents using Telegraphic Attack against those). For defense modifiers, like from Shields, Enhanced Defenses, etc, you'd double them and apply as a further penalty (which also means you could have higher resolution - instead of DB 1, DB 2, and DB 3 shields, you could have -1, -2, -3, -4, -5, and -6 shields; meanwhile Combat Reflexes would probably only impose a -1 and you could have half-levels of Enhanced Defense available that only give -1 each). This matches pretty well for equal skill (50% chance instead of 45%), but will deviate the further apart the characters' effective skills are.