Behind the Curtain: Damage Reduction
The damage reduction system changed significantly in the revised core rulebooks. The obvious change is in the new variety of methods to bypass a creature’s damage reduction: special materials, magic or aligned weapons, and types of weapons (slashing or bludgeoning) can all be the key to successfully getting past damage reduction.
The less obvious change is that it’s generally easier to break through a creature’s damage reduction even without the proper key. Most monsters subtract 5, 10, or 15 points of damage from most attacks, where prior to the revision this number might be as high as 40. A number like 40 tells players, “don’t even try it if you don’t have the right weapon.” A number like 15 sends the message, “You can try, but it’s going to be a lot harder.”
This booklet includes revised damage reduction entries for every monster in Deities and Demigods, Epic Level Handbook, Fiend Folio, Manual of the Planes, and Monster Manual II. If you’re converting other monsters that don’t appear in those books, follow these general guidelines:
• Make the damage reduction amount (the number before the slash) 5, 10, or 15. As a general rule, use 5 for weaker monsters, up to CR 4 or 5. Use 15 for strong monsters, CR 13 or higher. Use 10 for everything in between.
• Special Materials: If a monster had damage reduction bypassed by silver before, keep it silver unless a different material is more appropriate. Also use silver for baatezu devils, guardinals, and a selection of other creatures from the outer planes, particularly the lawful plane of the Nine Hells of Baator. In a few cases, you might combine this with good or evil (see Combinations, below). Use adamantine to bypass damage reduction in cases where a creature’s damage reduction is almost like hardness: for most constructs, creatures whose bodies are made of inorganic material, and for spell effects like iron body and stoneskin. Use cold iron for fey (often, even when they did not have damage reduction before), for the fey-like eladrins, for tanar’ri demons, and select other creatures from the outer planes, particularly the chaotic planes. It’s not a good idea to create new special materials except in unique circumstances: most adventurers have no reason to carry mithral weapons, for example.
• Weapon Types: If a monster took half damage from certain weapon types, replace this with damage reduction 5/other weapon types. For example, skeletons took half damage from slashing and piercing weapons; now they have damage reduction 5/bludgeoning. Rarely use weapon types as a bypass for damage reduction.
• Alignment: Allow aligned weapons to bypass the damage reduction of outsiders of the opposite alignment. Demons and devils have damage reduction #/good, celestials have damage reduction #/evil, slaadi have damage reduction #/lawful, and inevitables (despite being constructs) have damage reduction #/chaotic. Generally, fiends and celestials associate more strongly with evil and good, respectively, than with law and chaos.
The differences between lawful and chaotic fiends and celestials showcase in their racial vulnerabilities to special materials rather than aligned weapons (see Combinations, below).
• Magic and Epic: If nothing else fits, allow magic weapons to bypass a creature’s damage reduction. For monsters at very high CRs (minimum 20), consider using epic weapons instead.
• Combinations: You can use combinations of factors to distinguish monsters from each other based on CR and overall power. Many outsiders have damage reduction that combines special materials and alignments. For example, very weak tanar’ri demons have easy-to-bypass damage reduction: a good weapon or a cold iron weapon strikes unhindered. Moderately powerful tanar’ri benefit from damage reduction that is somewhat more difficult to bypass: you need a good weapon; a cold iron weapon won’t do. The most powerful tanar’ri have damage reduction that is even more difficult to bypass: you need a weapon that is both cold iron and good. As a rule of thumb, use “or” combinations for monsters of CR 3 or lower, and use “and” combinations for monsters of CR 16 or higher.
Also consider combinations of magic with either special materials or weapon types. A lich’s skeletal body is vulnerable to bludgeoning weapons, like a skeleton’s, but only if they are magic. A night hag is vulnerable to cold iron weapons, but only magic ones. In general, requiring two conditions (“and” combinations) makes a monster’s damage reduction more difficult to bypass, and is most appropriate for powerful monsters.
