Threshold by durability: some grittier or deadlier games may use the resilience and durability of a creature or object to affect its threshold, often as a replacement for resistance. In this variant, wearing armour doesn’t reduce damage taken, but rather increases the amount of Stress needed to inflict a Harm. This will mean that even the most heavily-armoured of characters will still be vulnerable to being worn down by enemy attacks, reducing how effective armour is overall.
This sounds really interesting to me. Do any existing 2d20 games use this? Is there any guidance to implementing it?
Not to my knowledge. But I don’t own all of the 2d20 products.
Only in the SRD, I’m afraid. And the math behind 2d20 is not easy (at least for me).
A “standard” attack (without any effects, that is), deals about 0.8 points of damage per Challenge Die (CD). Statistically speaking, you would need, on average, 7 CD to score the 5 Stress you need to cause a harm. If you rule that, with Armour 1, 6 Stress would be needed, you would need 8 CD (on average). With Armour 2, you’d need 9 CD, and 10 CD for Armour 3.
I’d test out with Armour levels of 1 (light) to 3 (heavy); 4 only in extreme circumstances (magical plate armour in a fantasy setting). If the effect is too brutal, one could think of adding armour to the regular Stress track, too.
I was thinking if I used this option, I would lower the default threshold to 4 or even 3. Then, as you say, armour ranges from 1 to 3. It would definitely lean in to a more gritty game. I haven’t decided if I want it that gritty though, heh.
That would end fights very quickly, unless characters are able to keep on fighting with a lot of wounds. Keep in mind that there are effects that modify attacks.
Vicious, for example, turns an average 0.8 per CD in a standard attack to a juicy 1.16 in a vicious attack. Piercing ignores one or more points of armour.
Even with a default threshold of 5, it takes a vicious attack only 5 CD to inflict one Harm to an unprotected target. It’d take 4 CD for a threshold of 4 and and 3 CD for a threshold of 3. Meaning that virtually everything more dangerous than an unarmed strike will, on average, inflict one Harm to an unprotected target with a vicious attack.