Damage Reduction (5e Other)
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The Value of DR
Damage reduction is one of the most potent effects in D&D. It is almost never used by core rules materials, and when it does appear, it is typically very conservative. The reason is that DR is a certainty, and that certainty stacks upon itself over time. The cumulative effect of even -1DR over the course of a single campaign can be worth thousands of HP that would have otherwise been lost. In a game where "1HP" means "ready for action, baby!", that is kind of a big deal. Worse, weapons in this game don't really scale their damage to match your level. The biggest bonus you can get from gaining levels is your ability modifier, at +5. That means the highest mundane, single-die damage possible is a 1d12 attack made by a level 20 character, with 20 in the relevant ability, dealing 6-17 damage.
|0||This is the core rules default for all gear, the baseline the game was balanced against.|
|-1||Immediately, at -1, you have negated the raw damage of unarmed strikes. Any character who lacks a strength bonus cannot hurt you with their fists any more.|
|-4||You are now eliminating the maximum raw damage of any 1d4 weapon, spell, or attack. This includes daggers and the lowest level martial arts die from monks. Anyone lacking a bonus for such an attack cannot hurt you with it.|
|-5||At -5, you are canceling out the highest possible ability modifier from an opposing PC, so any damage you do recieve from such an attacker is just from the raw die roll.|
|-6||This marks the point where no character, regardless their strength bonus, can hope to hurt you with their unarmed strikes. Additionally, any weapon, attack, or spell dealing 1d6 damage cannot harm you without a bonus. (A key example here, is that of a 10ft fall, or being set on fire, neither of which can harm you at this point in the absence of a DM ruling.)|
|-8||Here is the limit for the raw damage of 1d8 (or2d4) weapons, attacks, and spells. Again, without a bonus of some kind, these things simply can not hurt you any more.|
|-9||At this point, even a character with a +5 bonus to the damage cannot hurt you with a 1d4 attack, making dagger users a non-threat.|
|-10||Here, you are immune to the raw damage of 1d10 weapons, such as pikes and pistols.|
|-11||You are now immune to the highest damage possible on a 1d6 attack, rendering most enemies with shortswords irrelevant.|
|-12||You are now safe from the raw damage of a d12 (or 2d6, or 3d4) which includes things like lances, greatswords, muskets, and 20ft falls.|
|-13||This rank of DR protects you completely from 1d8 attacks, up to a bonus of +5.|
|-15||Here, you are completely immune to weapons dealing 1d10.|
|-16||At this point, you cannot be hurt by revolvers. That's pretty intense.|
|-17||And now you are protected completely from the highest single-die damage a character could inflict upon you. That fighter with 8 extra attacks, +5 STR, and a greataxe? You can safely ignore him. (I mean, unless he does something smart.)|
Dealing With DR
So, knowing the actual effects of damage reduction in the game, how can we use it in a balanced and meaningful sort of way? Here are all the methods I can devise.
DR in Encounter Design
First off, any DM who is running a game that includes damage reducing effects must consider the effect it will have on meaningfully threatening the player characters. The methods given for encounter building in the DMG were designed in its absence. Any character with DR may theoretically be a higher level challenge than usual for your monsters. For every -3DR, raise their assumed level by 1 for the calculation. (IE, a level 1 character with over -3DR counts as a level 2 character, past -6DR he counts as a level 3 character, past -9DR he counts as a level 4 character, and so on.)
This section may be a little harsh. Playtesting required.
Set DR Availability Limits
The easiest way is to just not hand out armor with a DR greater than some set limit! I have set two such limits for myself, one for a fantasy setting, and the other for a modern setting.
These limits actually still sound appropriate. Some playtesting may be required.
Fantasy Limit: -5
I set the fantasy armor DR limit at -5. -5DR means that the strongest non-monk unarmed strike will still deal 1 damage. The only weapons deeply affected by it are daggers and other d4 weapons, which have all of their raw damage eliminated at -4DR, meaning only enemies with a bonus in their d4 attacks can still hurt you. You will also still receive 1 damage from a maximum roll on a 10ft fall.
In a fantasy setting, the DR potentially available to players should be roughly equivalent to their tier of play, capping out at -4 during fourth tier. I envision -5DR only being available to characters who continue to adventure at maximum level, as a sort of max-level reward, much like an epic boon but not as potent. Characters of level 1 or 2 should not be able to access DR equipment AT ALL.
Modern Limit: -10
I set the modern armor DR limit at -10. The maximum, -10, makes you immune to pistols. In a modern setting, the DR availability limit should be roughly double the character's tier of play. (So a tier 1 character, shouldn't be able to access equipment more powerful than -2DR, for example.) Again, -9 and -10 DR should only be available to max-level characters as rewards for continued adventuring.
There is no Sci-Fi armor DR limit, because Sci-Fi really has no logical limits. It is reasonable to assume that, given enough time and technological innovation, people will eventually find some way to overcome any threat.
Make DR Expensive
Another method of reducing availability is to make gear with DR very expensive, and thus a goal that a character may work toward obtaining, though eschewing other possible rewards in the meantime. It is best to treat gear with DR as magic equipment, even if they are technically mundane, simply because they are so powerful, and thus more likely to appear as a treasure or quest reward in play. This chart assumes the items are magic. The GP multiplier is applied to their base value, which should be somewhere within an appropriate range for the item's rarity.
Another method to limit DR is to specify the type of damage it effects. For example, you could split DR effects into mundane and magical. Mundane DR only protects you from natural/physical damage, like rocks falling on your head, while magical DR protects you from supernatural effects, like magically manifested rocks falling on your head. You could go a step further and divy it up into damage types also. For example, a helmet with ear covering may give you -1DR against thunder damage, while fire-retardent clothing may give you -1DR against fire damage. Another option is to specify what damage sources the gear actually protects against. Realistically, even a suit of -6DR armor probably shouldn't protect you from a 10ft fall on the head, nor should it allow you to walk about, fully aflame, unscathed.
One of the main reasons DR is such a balance issue stems from its long-term impact. As previously stated, just -1DR over the course of dozens of combats can effectively save the character hundreds of HP, cumulatively. The way to mitigate this effect is to reduce the number of times it actually happens. There's, like, a million ways you can do this. Examples:
- Each time after a character gets hit, their DR is reduced by 1. (Or some other arbitrary #, like a hardness rating)
- Make it so that DR only counts sometimes. (Like, if the attack barely landed, such as within a 5 point difference of the target's AC. Or maybe each attack has 2d20 rolls, one to see if you hit, and the other to see if you get past the armor. Or maybe change critical hits to ignore DR.)
- Attach DR to a currency/resource, so it can only be applied to a limited number of attacks per rest.
Leaning on DR
Another resolution, in cases where DR is being used as a common mechanic rather than a really sweet treasure, would be to make armor with DR have comparatively low AC scores. That way, their actual defensive impact isn't quite as extreme. They'll be getting hit more, but taking less damage every time. If you balance it correctly against the types of encounters you build for your campaign, you can tweak it so that the net effect is roughly equal in the long run. (Same total amount of probable HP loss over multiple adventures)