Refining Thoughts on Ablation, Damage, and Death

This post by subjunctive moods earlier in the year got me thinking about ablative mechanics in combat, and Phlox’s All Damage As 1d6 reignited some of those thoughts.. We all know the pitfalls of Hit Points. But we also don't want our 97th-level Kobold Paramour to be as vulnerable as a newborn babe in battle.

A few constraints on a system occur to me:

• Any attack should have the possibility of incurring a mortal wound. A stiletto to the heart is as fatal as a beheading with a two-handed sword.
• If an attack is not fatal, it ought to increase the likelihood that the next is. Someone wrote an interesting piece a little while ago envisaging Hit Points as a character’s fate, which is interesting in this context.
• A combatant with greater skill at arms should have a greater chance of inflicting a mortal wound 
• A better-armoured combatant ought to have a better chance at avoiding a mortal wound 
• The number of die rolls must be kept to a minimum while still preserving randomness. I know some folks like fixed values, but I don’t.

This actually ties in with some of my earlier thoughts on Hit Points as an ability score, and refinement seems possible.

We roll Hit Points on 3d6. If you like, fighter-types roll highest 3 of 4d6, thief-types roll straight, and magicians roll lowest 3 of 4d6. Point is that it’s between 3 and 18. Add a Constitution modifier to the total if you like; if you’re using B/X scores, that makes the HP range 0-21. If you don’t do this, it’s 3-18.

An HP of zero is not immediately fatal, although a character so unfortunate is probably still going to have a short life.¹ Meanwhile, the Conan-type with a maximum HP of 21 is going to be mighty difficult to kill, as we shall see.

Secondly, we define ascending armour classes simply by their bonus. At its simplest, light armour is +2, medium is +4, and heavy is +6, with shields granting a +1. I’m rather fond of a variation on Robert Fisher’s piecewise armour scheme, but that has the potential to get rather fiddly. It’s important that the armour class stay fairly low, as

In contrast to my earlier efforts, we will need the to-hit roll and damage dice of D&D-like systems, but no more. When an attack roll is made, the attacker’s target number is the target’s Hit Points, with a bonus equal to the applicable Armour Class. This has the potential to be quite high, especially if magical armours are introduced, but much more than 30 is unlikely.

If the attacker beats the target number, then the defender loses Hit Points, and must roll on the Wound Table with a penalty equal to the damage² die rolled. If the attacker does not beat the target, then the defender only loses Hit Points.

Impact

The primary effect of this is fairly obvious. Early in a combat, most characters are going to be fairly difficult to damage, unless for some unaccountable reason they’re a fragile weakling who decided to explore a goblin-infested ruin in their dressing gown.³ But as their strength is sapped away, they will find themselves increasingly vulnerable, until at the last they are protected only by their armour.

Hence, a great warrior in shining plate with an armour class of +7 is invulnerable to a zero-level peasant armed only with a table knife. At first. But if exhausted by their prior efforts, the peasant might well find a weak point in their armour two times out of three.

A character at 0 HP, though, is not actually dead yet. They can fight. But they’ll be horribly vulnerable, especially should some effect come along that their armour doesn’t protect against. Falling rocks. The breath of a dragon. A liturgical book projected at high velocity.⁴

Weapons

One might, also, imagine weapons having differing effectiveness whether or not an opponent’s guard is overcome. A ‘typical’ warrior’s weapon, the arming sword, can comfortably be assumed to do 1d6 damage in all cases. This is a useful reference point. The peasant’s table knife might just remove one hit point⁵ on a failure, but a more useful 1d4 HP on a success. A knight’s dagger intended specifically for despatching a fallen foe might remove 1/1d8 HP. Useful in the intended situation, utterly useless against an enemy at their full strength.

There's probably merit in playing around with this a little more; since armour matters so much here, playing around with weapons-versus-armour makes sense.

For monsters, there isn’t actually much benefit to doing massive amounts of damage. The characters will never have more than 18 HP, and you don’t want to do so much in one go that it guarantees a one-hit kill. Remember that penalty on the wound table? If it’s a 2d6 table, a 12-point hit is unsurvivable. There’s probably no point going bigger than that, they don’t get any deader.

Healing and Advancement

The system really needs Hit Points to stay in that 3-18 range, or 0-21 if we’re adding Constitution. It’s probably better if you don’t, but I’m not your boss.⁶

On the one hand that makes running out of them quite likely, so any healing options you offer want to be short and frequent, rather than big and flashy. Regaining 1d4+1 HP means quite a lot when you’ve never got more than 18.

But on the other hand, a healing rate of 1-3 HP/day is never going to run to weeks and weeks, helping to avoid the problem of the wizard getting their spells back with a night’s rest but the fighter having to lay up until the next season.

Advancement bumps into a similar problem, in that we do probably want our 97^th level Kobold Paramour to be about as tough⁷ as such a thing gets. Fortunately the solution seems fairly easy. At intervals when an increase in HP might be called for, roll 3d6. If this exceeds current HP, the character takes the new value. Otherwise, it remains unchanged.

Is this any good? Not sure. But I think it achieves something similar to Phlox’s goals. I’ve not mathematically tested it, but the chance of death should be higher at high HP values, and lower at low HP values than straight ‘death at 0 HP’ rules.

1: Excitement is optional. But almost certainly short.

2: We’re going to need a better name, as this isn’t damage.

3: For some reason we think these people are intelligent, though their name strictly means over-wise, in the same way that ‘drunkard’ means over-drunk.

4: Magic missal? I’m here all week, remember to tip!

5: Seriously, damage is such a handy term.

6: Unless I am, in which case well done me for the promotion, and get back to work.

7: Like old shoes, I’m guessing.