On Elemental Damage

D&D 5e has thirteen damage types. This post is concerned with the most fundamental of these damage types - the most primordial ingredients in the great soup of D&D combat. No, not bludgeoning, piercing, and slashing - the elements!

There are five damage types which are generally considered "elemental":

Acid. The corrosive spray of a black dragon's breath and the dissolving enzymes secreted by a black pudding deal acid damage.

Cold. The infernal chill radiating from an ice devil's spear and the frigid blast of a white dragon's breath deal cold damage.

Fire. Red dragons breathe fire, and many spells conjure flames to deal fire damage.

Lightning. A lightning bolt spell and a blue dragon's breath deal lightning damage.

Thunder. A concussive burst of sound, such as the effect of the thunderwave spell, deals thunder damage.

What's that you say? "But the elemental planes in D&D are air, earth, fire, and water"? Well, I'm talking about damage types, not the four elements. What's that? "The chromatic dragons, which more or less personify the elements, represent acid, cold, fire, lightning, and poison"?

Well, trust me. These are the five elemental damage types. Acid and thunder are definitely elements. And I have proof! Absorb elements is a spell which can be cast as a reaction, "which you take when you take acid, cold, fire, lightning, or thunder damage". The Elemental Adept feat allows the character to specialize in a damage type, choosing between acid, cold, fire, lightning, and thunder.

Moving on, there is something to be said about the fact that D&D's damage types come into play only when and if a creature is resistant, immune, or vulnerable to a type of damage. Sure, skeletons are vulnerable to bludgeoning and trolls can't regenerate if you hit them with acid or fire. Demons have a bunch of resistances that make them marginally more difficult to fight. But that's pretty much it. 

I think every damage type could use a little love - a reason to use one type over another in a given situation, besides overcoming the "challenge" of resistances. To start, though, here are my ideas for just the elemental damage types:

• Acid: Effective against pretty much anything that burns. Ineffective against oozes, water elementals, and any creature submerged in water. 
• Each instance of acid damage reduces a creature's nonmagical physical armor class by 1 (i.e., it does not affect adjustments from Dexterity or magic), to a minimum of 10. At AC 10, worn armor is destroyed. Natural armor heals at a rate of 1 AC per day. 
• A creature killed by acid damage has a part or all of its body dissolved (requiring more powerful resurrection magic to bring them back to life). Player characters reduced to 0 hit points by acid damage usually lose at least a hand or a foot, or suffer serious scars.

• Cold: Super effective against plants and creatures accustomed to warmth. Ineffective against creatures magically adapted to the cold (i.e., yetis) and against undead. 
• Freezes water and other liquids. Underwater, cold spells which originate from the caster (i.e., ray of frost, cone of cold) have half range.
• Each instance of cold damage reduces a creature's speed by 10 feet until the end of their next turn (reminder: when their speed reaches 0, flying creatures fall unless they can hover).
• A creature killed by cold damage is frozen solid for a number of days equal to the level of the spell which killed them. This preserves the body similar to a gentle repose spell. For the duration, the creature is basically petrified. Any potions, poisons, or oils the creature carried are frozen for the same duration. Quick-thawing the creature with a heat source of any kind is generally ill-advised.

• Fire: Super effective against dry, papery creatures (i.e. scarecrows, mummies, and origami golems, a tumbleweed blight but not a shambling mound) and creatures accustomed to the cold. Instantaneous effects are ineffective against water elementals and any creature submerged in water. Sustained effects, however, can boil them alive.
• Sets thing on fire. Don't cast fireball in the ancient library, obviously. Fire also doesn't care if things are worn or carried. Clothing and spellbooks are set on fire just the same as scenery. 
• Each instance of fire damage causes a flammable creature or object to take one die of damage (die size determined by the original effect, e.g., 1d6 from a fireball or 1d10 from a fire bolt) at the end of each of its turns unless it takes an action to extinguish the fire or submerges itself in water.
• A creature killed by fire damage continues to burn. Its body becomes ash in a number of turns equal to 9 minus the level of the effect (cantrips and equipment like torches and burning oil count as level 1). A player character reduced to 0 hit points due to fire damage also continues to burn (meaning they automatically fail a death saving throw every round). Creatures/player characters reduced to 0 hit points by a 9th-level fire spell/effect (an ancient red dragon's breath) are immolated instantly.

• Lightning: Super effective against wet creatures and those made of/wearing metal. Ineffective against creatures made of stone (earth elementals, gargoyles, stone golems, etc.) or rubber (rubber band golems).
• Water and metal conduct electricity. Lightning attacks made against a wet creature or a creature made of or wearing metal have advantage. Wet creatures and creatures made of or wearing metal have disadvantage on saving throws against lightning effects. When a lightning effect targets a creature in the water, all creatures in that body of water are affected. No saving throw.
• A creature that takes lightning damage loses its reaction until the start of its next turn.
• Lightning can defibrillate dead creatures. A creature with access to a lightning spell can attempt a spellcasting ability check when adjacent to creature that has been dead for less than 1 minute. The DC equals 20 + the number of rounds the creature has been dead. On a success, the creature regains 1 hit point. If the creature is a player character, a success instead cancels out one failed death saving throw, allowing the character to continue making death saving throws.

• Thunder: Super effective against creatures with keen hearing (many animals and animal people) and those made of glass (stained glass golems). Ineffective against deafened creatures or within a zone of silence.
• A creature that takes thunder damage is deafened until the end of its next turn. While deafened, a creature has disadvantage on any checks or saving throws made to maintain balance (i.e., Acrobatics, resisting the prone condition) and cannot cast spells with verbal components.
• A creature killed by thunder damage which is resurrected is permanently deafened unless magical healing which restores lost body parts is employed. A player character reduced to 0 hit points by thunder damage who does not die is instead deafened for a number of days equal to the level of the effect.

And there you have it! Is this good? I don't know, but it's something! I really like the idea of taking a more "common sense" approach to 5e next time I play it. I think D&D in general and 5e especially sings much more sweetly when you let yourself be immersed in the fiction instead of the rules. 

Hopefully, these rules take what are normally nondescript beams and blasts of different colored energies and turn them into lifelike elements that create their own varied effects.