Kaiju already exist in D&D. And, using the rules, you can already fight them.

But these mechanics tend to shrink the scope of these creatures. You can square off with a tarrasque, for example, in basically the same way you would with an ogre and poke at it with a spear until it dies. It doesn’t really matter how many squares the tarrasque takes up on the battlemap; it doesn’t feel like you’re fighting something that’s truly enormous. (Particularly if you picture the scene and realize you’re really just tickling its toenails.)

So what should a fight like this look like?

For our touchstones, let’s consider the Bahamut fight form Final Fantasy VII: Advent Children:

The dragon fight from God of War 4:

And the Dweller in Darkness fight in Shang-Chi: Legend of the Ten Rings:

(Video Coming Soon!)

Which is particularly notable, I think, because it features kaiju on both sides of the fight, with human combatants wedged between them.

In each of these fights, there are also common elements that jump out for me:

• Ranged attacks obviously feature quite a bit. (Although they can usually be described as bouncing almost harmlessly off the creature’s thick hide, unless a particular weak spot can be hit.)
• In order to be effective, characters have to literally be on the kaiju.
• The fights feature lots of terrain being casually devastated… including, frequently, the places where the PCs are standing or were just standing a moment before.

Finally, for something a little different, let’s add literally this entire game:

Shadow of the Colossus has a very different pace from the other examples, which I think is useful for keeping in mind when considering the breadth of what kaiju encounters can be.

HEY! I DON’T WANT THAT!

Some of you reading this are undoubtedly thinking, “I don’t want humans running along dragon spines! It’s silly! I want grounded, gritty fantasy! It’s not realistic to think that a normal human could solo Smaug with a sword!”

Short version: These rules are not for you.

Long version: Neither is D&D. By which I mean that the unmodified rules for D&D already let high-level characters solo Smaug. So if that’s not the sort of thing you want your D&D characters to be doing, you’re already having dissonance with the system. Check out E(X): The Many Games Inside the World’s Most Popular Roleplaying Game for an approach that will let you dial in the experience you want.

DEFINING YOUR KAIJU

There are a lot of big monsters in D&D. What counts as a kaiju?

Some key things that I, personally, would think about are:

• Is this monster big enough that it’s basically part of the scenery? A very active part of the scenery, yes, but basically the size of a building or even bigger.
• Is this monster so large that it’s difficult to imagine someone standing on the ground next to them even being able to reach their vital organs?
• Is this monster capable of trivially destroying human-scaled objects while barely even noticing that they’re doing it?

I think the lowest cut-off that makes sense to me (again, speaking only for myself personally) would be at least the size of a storm giant. (Storm giants stand 26 feet tall, are probably 6-7 feet across at the shoulders, and their knees would be about 8 feet above the ground.) And I’d probably want to aim a little bit higher than that.

So as you’re looking at the kaiju rules below, think about what scale of creature they feel right for. Here are a few options to consider.

OPTION #1: GARGANTUAN CREATURES

The simplest metric would be to just declare all Gargantuan creatures to fall under the kaiju rules. This conveniently includes all our likely suspects: tarrasques, rocs, dragon turtles, ancient dragons, and purple worms.

Using this option, the rules for fighting kaiju would only apply to Large or smaller characters. (Huge or Gargantuan characters are close enough to the kaiju in size that no special rules need apply.)

OPTION #2: THREE SIZES LARGER

Alternatively, we could extend this logic to say that any creature three size categories larger than you is considered a kaiju. This would mean that Small creatures would have to treat Huge creatures as kaiju.

This makes a certain amount of sense. If we use our previous example of a 26-foot-tall storm giant, its size relative to a halfling would be like a 50-foot giant relative to a human. (This would actually be the same height as a tarrasque!)

The drawback, of course, is a practical one: PCs can be both Small and Medium size. When encountering Huge creatures, some of the PCs would consider them kaiju and others wouldn’t. You might consider this a feature (and even a great roleplaying opportunity), but it would undoubtedly add the possibility for confusion and probably some potential issues with balance.

OPTION #3: TWO SIZES LARGER

This is the option that treats storm giants and treants as kaiju-class foes for human opponents. However, it would also mean that Large creatures would be treated as kaiju for Small PCs, and Large opponents are actually quite common in D&D. So this would almost certainly result in the kaiju rules being used frequently.

OPTION #4: BESPOKE KAIJU

It’s a kaiju if I say it is.

You might choose this option if you want to include specific corner cases (like storm giants, who are near the high end of the Huge class). This can also be appealing if you just want to include the occasional kaiju-themed encounter in your campaign, but then not worry about the kaiju rules every single time some big monster shows up for a tussle.

THE KAIJU RULES

In order to engage a kaiju, you enter its space while moving or as a reaction to being the target of a kaiju’s melee attack. This usually requires some form of check (e.g., a Strength (Athletics) to jump onto the kaiju from above or a Dexterity (Acrobatics) to grab on as it flies past). This check is contested by the kaiju’s Dexterity (Acrobatics) check to avoid the little pests.

Being engaged with a kaiju usually means that you are physically on the kaiju in some way. Being engaged is an exception to the normal movement rules preventing you from willingly ending your move in another creature’s space. As long as you are engaged with the kaiju, you will be carried with the kaiju when it moves.

Characters who are not engaged with the kaiju suffer disadvantage on their melee attacks targeting the kaiju. Characters engaged with a kaiju gain advantage on their melee attacks targeting the kaiju.

Shake Loose: As a special melee attack, a kaiju can attempt to shake off anyone currently engaged with it. When they do so, all engaged characters must succeed on a Strength (Athletics) or Dexterity (Acrobatics) check contested by the kaiju’s Strength (Athletics) check. On a failure, the engaged character is shaken loose into an adjacent space of their choice and is no longer engaged with the kaiju. They must also succeed on a DC 15 Dexterity saving throw or suffer 2d6 falling damage (or more if the creature was flying at a height greater than 20 feet).

Siege Monster: All kaiju are given the Siege Monster ability. They deal double damage to objects and structures.

Kaiju Destruction: All kaiju are given the Kaiju Destruction ability. They can deal damage to structures within reach as a bonus action.

Design Notes: These rules are deliberately quite simple. Our goal is not to weigh the system down with a lot of detailed mechanics, but rather to provide a straightforward prompt for DMs and players to dynamically describe these battles.

ADVANCED KAIJU RULES

Flying Characters: Flying characters and characters on flying mounts do not suffer disadvantage when making melee attacks against a kaiju.

Engage with Vantage: If circumstances allow a character to attack a kaiju’s vulnerable areas, then, at the DM’s discretion, it will not be necessary to engage with the kaiju in order to avoid suffering disadvantage on melee attacks against it.

For example, a character might be located on a wall or in a tower that the kaiju is passing by. Or they might be riding another kaiju.

Such vantage points do not grant advantage on attacking the kaiju, but may grant advantage on skill checks to engage the kaiju.

Hey! I Was Standing On That! When a kaiju destroys a structure that a PC is standing on, they can attempt a DC 15 Dexterity check as a reaction to land on the kaiju and immediately engage it.

Helping Others to Engage: This can be done with a standard Help action, granting advantage to the aided character’s skill check to engage the kaiju.

Knocked Off: If a character is knocked off a kaiju, the DM may allow them a DC 12 Dexterity saving throw to grab hold of a lower point on the kaiju and remain engaged. In addition to deliberate enemy action (kaiju gnats or other allies fighting the PCs on the kaiju’s back), the DM might also call for such saving throws (possibly at a higher DC) in response to environmental conditions — when the kaiju smashes through a wall or flies through a waterfall, for example.

ROLEPLAYING KAIJU

Nothing in the rules of 5^th Edition requires motion, but these creatures are simply massive and even a single step that might only be a small adjustment for a human-scale character can easily chew up significant distance.

So you’re under no compulsion, but describe your tarrasques not only staggering back from mighty blows, but actually moving across the battlefield as they do so (and even chewing up their bonus action to unintentionally smash through a wall along the way). Have your ancient dragons constantly swooping back and forth across the battlefield.

Also keep in mind that these gargantuan creatures may not immediately pay any attention to the PCs, or simply disregard them as irrelevant. (In much the same way that we might see a chipmunk or sparrow in the woods and just… not care that much.)

This, in turn, sets up the moment when the kaiju is suddenly VERY MUCH PAYING ATTENTION TO YOU. That’s a big moment. Play into it.

It’s not unusual for the property damage inflicted by a kaiju to unwittingly prove its undoing: Leave large, heavy, sharp objects dangling precariously and then let the kaiju linger under them for a round or two.

REVERSE KAIJU ADVENTURE

The limited range of size categories in 5^th Edition (compared to previous editions) prevents this idea from being directly supported by the rules, but it might be fun to frame an adventure or encounter in which the PCs are the kaiju.

Their opponents might be diminutive Lilliputians or perhaps a scurrying mass of anthropomorphized mice. Either way, the kaiju mechanics work the same in both directions, and you can describe the little folk clutching the PCs’ hair or scurrying inside their armor.

Another option along these lines is to give the PCs temporary (or permanent) control over a gargantuan construct, which can benefit from its status as a kaiju-class combatant.

A cerberus spawn is a large, three-headed dog. They usually have sleek, grey-brown fur, although some are jet black. One can often seen their veins, which glow like red-hot lava through their skin. Their eyes, too, glow red above their slavering maws.

Spawn of Hades. Cerberus spawn are said to be the get of Cerberus itself, the great hound who stands guard upon the gates of Hades. Like their forefather, cerberus spawn are used throughout Hades to keeps souls from escaping their gaols and masters.

Guard Dogs of the Lower Planes. From Hades, the cerberus spawn have spread throughout the Lower Planes, where many demons and devils employ them as guardians. Even wild packs are sometimes seen, roaming the Abyss, feasting upon the damned souls of Avernus, or  adding their howls to the lamentations of Cocytus.

Ghost Hounds. The gifts of cerberus spawn are also renowned on the Material Plane, where their affinity for souls makes them expert trackers of ghosts and other incorporeal undead.

Packs of cerberus spawn are also often brought to the Material Plane by more powerful fiends. They are sometimes abandoned by these masters, or left feral after mortal heroes dispose of their keepers. Such hounds often seek a way home, although some find the easy prey of the mortal world to their liking and settle down.

Cerberus spawn breed true, but rarely (only going into heat once every thirteen years), so fortunately these packs rarely become endemic. Druids often seek to eliminate them, however, because they tend to violently displace native predators. (It’s not unusual, for example, to find dead wolves marking the limits of a cerberus spawn’s territory.)

CERBERUS SPAWN

Large fiend, neutral evil

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Armor Class 15 (natural armor)

Hit Points 85 (10d10+30)

Speed 50 ft.

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STR 22 (+6), DEX 9 (-1), CON 17 (+3), INT 8 (-1), WIS 12 (+1), CHA 5 (-3)

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Skills Perception +5

Senses darkvision 60 ft., passive perception 15

Languages Infernal

Challenge 5 (1,800 XP)

Proficiency Bonus +3

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Three Heads: A spawn has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Soul Scenter: A cerberus spawn gains advantage on Wisdom (Survival) checks related to ghosts and similar undead.

Magic Resistance. A spawn has advantage on saving throws against spells and other magical effects.

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ACTIONS

Multiattack. The spawn makes three bite attacks.

Bite. Melee Weapon Attack. +9 to hit, reach 5 ft., one target. Hit: 17 (2d10+6) piercing damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be knocked prone.

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This video is a sequel to Every Edition of D&D: A Quick History of the World’s First Roleplaying Game, and it’s a deep dive into all the oddball corner-cases that I missed (or that others insisted I’d missed) the first time around. Some of them, like the D&D board games, you’re probably familiar with, but I’m guessing that everyone will be surprised by something on the list. (I was!)

Am I still missing something? Let me know!

I’d mentioned on my last video that my efforts to set up a better video production pipeline by hiring a professional editor had spectacularly failed when they were completely incapable of turning in a single professional video that could actually be shared. I’m still working on fixing that issue so that we can get more regular updates on the Youtube channel! I’ll keep you posted!

Go to Table of Contents

AVERNIAN ENCOUNTER DISTANCE

As described in Part 7B: Avernian Hex Map, the Avernian Hexcrawl features unique terrain types. You can use the following table to determine encounter distance in Avernus.

AVERNIAN REACTION TABLE

Reaction checks in Avernus are made by rolling 2d6 on the following table.

If you roll doubles, however, the encounter’s reaction will be deceptive, in which case the encounter’s reaction will appear to be the opposite result on the table:

• Immediate Attack/Hostile encounters will appear incredibly friendly and welcoming… right up until they slip the knife in.
• Threatening encounters will appear cautious, most likely using that posture to put the PCs at a disadvantage. (“Your weapons scare me! Put them down and we can talk!”)
• Cautious encounters will attempt to scare the PCs away with a display of dominance.
• Neutral encounters are unchanged.
• Amiable encounters will present behavior that seems overtly hostile, but most likely due to cultural differences. (The demon is brandishing its venom-glistened fangs at you so that you’ll see that it’s having its venom sacs discharge a clear fluid instead of poison!)

Deception is possible in any setting, of course. By having it systemically occur one-sixth of the time in Avernus, our goal is to leave the players feeling unsettled and uncertain. Hell is an alien environment filled with lies and liars.

FACTION ALLEGIANCE TABLE

Devils encountered in Avernus will usually belong to or be allied with a faction. (Hell is all about its hierarchies.) You can randomly determine an encounter’s faction using this table.

Go to Part 7I: Avernian Rumor Tables

Go to Table of Contents

PROCEDURAL ENCOUNTER TABLE

Tip: The Procedural Encounters table will generally produce homogenous encounters with only a single creature type. Although it requires more dice rolling (and some creative interpolation to explain the results), you can quickly generate mixed encounters by rolling twice and halving the number of creatures of each type appearing (round up).

You may discover that it’s actually easier to improvise creative encounters by generating mixed results, because the pairing of different devil types will spur your creativity in explaining what they’re doing together.

STYX ENCOUNTERS

ENVIRONMENTAL ENCOUNTERS

ROCKS OF THE DAMNED: Some of the rocks in Avernus seem to have tormented faces etched into them.

BONEFIELD: A field of bleached bones lying half-buried in the dunes or choking a razor-sharp ravine These are remnants of some ancient battle. (Avernian bonefields often feature titanic skeletons that will tower over the PCs.)

AVERNIAN FIREBALLS: Travelers in Avernus are periodically plagued with balls of flaming energy that spontaneously erupt without apparent reason. They inflict 5d6 fire damage, with a DC 15 Dexterity saving throw for half damage.

INFERNAL WRECK: 1d3 wrecked infernal war machines. The PCs can likely scavenge parts from them. There’s a 1 in 6 chance that the machine can be repaired without completely overhauling it.

OPPRESSIVE CONDITION: Trigger an oppressive condition, as described in Part 7B. This will exist in addition to any oppressive conditions already present.

AVERNIAN WARLORDS

See Part 7E: Warlords of Avernus for more details on the warlords. You can roll on the table below to randomly determine which warlord’s faction has been encountered. There is a 1 in 4 chance that the warlord is present for the encounter, otherwise it’s just an appropriate squad of their gang members (most likely riding infernal war machines).

DANGEROUS DEVILS

Go to Part 7H-D: Advanced Encounter Options