Concentration for Martials

[Theodoxus]

I prefer ablative armor over DR (or at least large DR numbers). If I were to use DR, I'd run it as HAM, but using PB instead of a blanket amount. Heavy armor DR = PB; Medium armor DR = PB/2, and Light armor DR = PB/3.

I think that would keep DR functional without wrecking bounded accuracy. But I would definitely add an ablative nature to armor, which would allow for higher ACs (if desired) - but could also allow for better fine tuning of effects. (Beyond the complexity of B/P/S vs armor types, which definitely slows down combat sans an artificial DM.) But if you had a rule that say, Fighters and Paladins in Heavy Armor had double the DR (or twice the Armor Hit Points) for attacks that hit armor, then a Wizard getting Heavy Armor Proficiency via a Cleric dip isn't getting as much benefit as the same starting Fighter or Paladin instead (and thus losing spell slot progression for the sake of added armor protection). Likewise, something like a rule for Barbarians where their DR is doubled when they're NOT recklessly attacking, as they're getting more defensive value when they're not opening themselves up to retaliation, adds a bit of tactical decision making for the Barbarians player.

Of course, something should probably be granted to unarmored defense in lieu of DR; though probably just adding PB to AC would be sufficient. Makes Monks in particular more evasive.

As for how ablative armor works, my current version is a baseline AC of 8+PB, called Defense. So, anything that rolls below that is a full miss, no damage. Armor then provides an AC value that is added to that number. Take the current AC of an armor, subtract 10 and add the remainder to your Defense (+ Dex if the armor is Light or Medium (max Dex +2/+3 with MAM). That is your AC. Anything that hits between your Defense and your AC hits armor. Armor is rated with a number of Armor Hit Points (AHP) that absorb damage from a hit. If a hit deals more damage than the remaining AHP value, the remainder carries through to the PCs HP pool, and the armor is currently useless (proving neither DR (if applicable) nor AC - so the Defense is now 8+PB+Dex. Obviously, a hit that is higher than the AC ignores the AHP completely and goes straight to PC HPs (whether it also bypasses DR is another question - I rule it does).

The amount of AHP provided is more campaign specific than fixed; for players, they're always wanting more - but taking other forms of 'temporary HP, from THP to the arcane shield provided by Abjuration, I wouldn't recommend more than 10 AHP per AC provided. It shouldn't make it longer to take out a PC than normal.

Of course, spells with saving throws bypass armor as normal. Spells with attack rolls can hit and deal damage to armor. If DR applies or not, is again, a DM call. In a simplified version, I'm ok with DR working.

Repairing AHP can be as simple as an appropriate skill check (Leather working, smithing) over a short rest. Might repair 1 AHP per point of the roll; no minimum DC. Might repair a fixed amount per rest. Using something like Mending might work (despite the spell description not accounting for it). I'd recommend no more than 10 points per casting. Even completely rent armor should be repairable, though you might need to scrounge up additional material if you're not using magic.

For monsters that wear armor, I use a simple formula of 1/2 HP = AHP, and 1/2 HP = new HP value. The AC, I keep the same, and just have a range of 10 to AC hit armor. This does make monsters generally easier to kill (especially with saving throw spells), but I see that as a plus anyway.