Fantasty Martial Arts

Martial systems develop in response to their environments and the culture of the time. For fantasy settings, those environments include giant monsters, magic, and other general weirdness that would absolutely affect all martial systems everywhere in the setting. Unless your setting has only humans, or only humanoids with a similar height, reach, number of limbs, etc., your fantasy martial systems are going to have radically different considerations.

Any of these martial arts can be taken in place of a language for Monks, Fighters, Barbarians, Paladins, and Rangers. Or maybe as a Feat, GLOG Template, what have you.

Source

Orcish Aquathlon

A specialized form of underwater striking and grappling, which turn out to be a little different when gravity it a bit more subjective. Special attention is taken as to one's buoyancy, as the states of rising, neutral, and sinking often affect what limbs come in reach.

Being above your opponent is generally considered a winning position, as it allows you to keep your opponent from rising and accessing air, usually by kicking them in the face.

Practitioners receive no penalties when fighting underwater, and the amount of time they can hold their breath is doubled.

Novan Tunnel Fighting

Practiced in the drow volcanic city of November. Utilizes a braided training cord for grappling. Military uses use a sharp unbreakable cord that can slice through unarmored appendages with ease.

Techniques are divided into two categories: feet first, and head first. Feet first techniques emphasize pins and kicks while braced against a surface. Head first techniques make use of the braided cord to snag and drag limbs around sharp surfaces or garrote your opponent. Numerous pins have been developed to asphyxiate or otherwise incapacitate your opponent in confined spaces.

A sport version of this exists. An arena is constructed either vertically or horizontally, with one side composed of glass for spectators to see into. A rat maze is then constructed out of shaped stone and dirt. The fighters each start at one of multiple entrances and must find each other. This is done in total darkness. Those without darkvision will find learning the sport difficult.

Practitioners receive no penalties when grappling or using Light weapons when squeezing. Movement speed is 1/2 rather than 1/4th while squeezing.

Suthlands One-Armed Boxing

Numerous wars with the orcs of Shadowmountain have left many a veteran in the Suthlands missing eyes, noses, ears, and limbs. (The Shadowmountain orcs, contrary to the propaganda and scary stories, don't typically execute captives or kill opponents in battle. Instead they prefer to mark them by mutilation as a sign to other orcs that this person lost a fight, and hence might be below their effort.)

Missing arms are common. In this vacuum a fighting style was developed to make use of the lack of two arms: one-armed boxing. There's an emphasis on power and keeping the 'stump' protecting the head or body.

Practitioners deal more damage with a punch (but only with one arm), and only every other round of combat.

Troll Art

More martial art than fighting system. Makes use of quasi-religious meditation. The monk makes use of their mastery of their body in order to regenerate like a troll. Exemplary practitioners can even regrow limbs and rejuvenate aging body parts. Legendary practitioners can grow limbs and body parts that they didn't have originally, like a hydra sprouting new heads.

The mythical founder figure of the Troll Art was a woman named Fatoumata Din, and was described as to be so powerful in the practice that, with sufficient time and calories, could clone herself entirely.

Practitioners can use an action to gain temporary Regeneration. Available to monks only. No other adventuring professions has the introspection required.

Don't Eat Me

A self-defense system designed to assist the user in avoiding being predated by larger creatures. Applies to anything that could scoop you up and eat you whole: trolls, giants, kraken, giant birds.

Originally observed in small prey animals (to human), including mice, rats, and bugs. Rats would go on to be formal instructors in the school, opening academies to teach their (to them) giant neighbors.

First Rule of Don't Eat Me: If you can run, RUN!

Second Rule of Don't Eat Me: If you can hide, HIDE!

Third Rule of Don't Eat Me: Picking you up? Bite! Bite! Bite! Stab! Stab! Stab!

Fourth Rule of Don't Eat Me: If it drops you, scurry away!

Fifth Rule of Don't Eat Me: Out of options? Play dead! (Maybe it'll lose interest)

Sixth Rule of Don't Eat Me: Never travel alone. Always has at least three people (most big things have only two hands to grab).

Practitioners receive advantage to get out of grapples by larger creatures, and get an AC bonus to their attacks. Coincidentally, it also gives a minor boost to disarming techniques.

Armstrong's Long LAW Arms For Harm

For use with Armstrong's Long LAW Arms! What's the point of having a Long LAW Arm if you don't know how to use it? Having synthetic arms twice or three-times the length of somebody else's can be a big advantage! It can also be a liability if used improperly. Well, Armstrong's got the solution for you! A nifty fighting system to use with your superficially-extended limbs!

Armstrong advertises that the best use of the Long LAWs is to use them for slapping. Slapping really hard and fast, like a windmill arm falling from the heavens!

Practitioners ignore the penalties for using long arms. And they may or may not be taken seriously by other martial artists.

Glare Art

Makes use of body contortion and special paints to produce terrifying images. In this sense, the Glare Art is much more so art than any of the martial systems above. Derived from observance of petrifying creatures, such as the Basilisk and Medusa. Adherents will essentially practice making faces, until they can make a face that is truly terrifying enough to stop anything with sight in its tracks.

Being able to warp the face in this manner takes quite a lot of practice and skill, with varying levels of mastery present in the orders that teach them.

Initiates will begin by practicing spooky faces in a mirror, and will be taught how to formulate and apply the proper paints that emphasize certain features. Eventually, if they're good enough, they'll progress to higher stages by testing out their abilities on small plants.

Past a certain level of power, though, we pass beyond the realm of safe practice. Masters are capable of petrifying, truly petrifying someone with their glare alone. It takes a lot of energy and special knowledge of facial makeup to produce such an effect, but at a certain point it becomes outright dangerous to practice. There are several fables of overconfident masters using their powers wantonly, and all eventually catching glimpse of themselves by some fluke and self-petrifying.

Practitioners get advantages to intimidate their opponents. At higher levels they can Stun or even Petrify them at a glance. Available to monks only. No other adventuring professions has the introspection required.

Gods, Dungeons, Nemesis, Doom

I'm fond of emphasizing the role of religion in worldbuilding, so here's a mechanical take for Tidelock, with a kind of Greco/Roman bent.

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Dungeons are a weird space. It's just kind of assumed that you can just... murder everything inside of one without consequence? Like dungeons are a truly lawless place, free of the moral trappings of society and religion. What happens in the dungeon stays in the dungeon. There are some exceptions, sure, but by and large murder and plunder in the dungeon is the norm. I mean, that's what one does in dungeons, right?

This assumption can be applied to most 'wilderness' places in your traditional RPG campaign. You go places and kill stuff and take loot, right? And nobody bats an eye at the adventurer for doing so.

...But what if that wasn't the case? What might that look like? What if the religious consequences for murder were quite real and explicit, for everyone? (Not just for goody-two-shoes paladins and clerics.)

Like, what if you killed a goblin, and then the goblin god was got pissed at you for (in its eyes) murdering one of its followers? And then the goblin god would bide its time until the right moment to, like, have a rat bite at your ankles while you're fighting, causing you to take a spear to the face?

The "Dungeon" is Desecrated

Desecrated in a religious sense: it is a space within which the relevant gods no longer cast their gaze. It is not a sacred, or even a normal space - if it were, there would be religious consequences for plunder and killing. In the true "dungeon" there are not.

Some dungeons are desecrated. Some have been that way for a very long time (such as old ruins). Some are not (yet). In order to do your killing and plunder without running the risk of gaining Nemesis or Doom (see below), you're going to need to consult with a good faith cleric, priest, druid, or other religious sage, in order to determine whether this particular space has the protection of a god.

So, say you're an adventurer!

How does one determine whether a space is protected by a god or not?

• Lore
• Rumor
• History (desecrations and consecrations are important events. People will remember them, and tell their kids and grandkids about them.)
• Consult or contract a sage, priest, druid, monk, scholar, etc. to find out.
• Be a cleric, druid, occultist, etc. and do the augury yourself to determine if there's something here.
• If there's religious stuff around (altars, priests, religious art), it's a sure thing that at some point it is, or was.

Does the place you want to loot and possibly kill within have the protection of a god?

• No: Well, have at it, then!
• Yes: Better get protected by a god then, or have it arranged to strip the protection from the place. Consult a priest.

You don't want this to happen to you!

"Justice and Divine Vengeance Pursuing Crime" - Pierre-Paul Prud'hon

With this is mind, the adventuring party can make some informed decisions about the places they want to delve and the things they might want to hurt.

Ruins will typically be desecrated dungeons, and have likely been so for a long time. Chances are that one can avoid divine retribution in these godless spaces. People like to avoid these for exactly this reason. It might be full of monsters without sentience: undead and the like. Conspiracies and outlaw cults might drag people to these places so that they can do their horrible rituals without the notice of gods and men. Ruins are innately risky places.

Caves, Groves, and other Natural Spaces may or may not be deconsecrated. Are there religious markings anywhere about it? Does it have a sacred animal inside? Is a Druid present? You can consult a Druid if one is unsure whether that space is okay to take from or not, or take a (probably) safe risk if you don't see any markings.

Forts, Temples, Shrines, Hamlets, or other places that have People are likely not only to not  be deconsecrated, but are probably specifically consecrated: under the watchful eye of one or more gods. Not recommended to attack or loot unless you're either preemptively absolved (morally, legally, religiously), have significant divine protection, or you're prepared to accept some divine retribution (see below).

Outlaws carry their desecration wherever they go. There's very rarely religious consequence for killing one or taking their stuff. It's still possible, though, for outlaws to gain religious protection from some other source than from the society which outlawed them. A pious outlaw is rare indeed, but one can become a serious problem for the authorities. It's not uncommon for outlaws to kidnap priests, monks, and druids to use as hostages in case somebody comes after them - a priest who dies in a skirmish will likely taint everyone involved.

Nemesis and Doom

When characters kill things that are still under a god's protection, steal or deface holy items, exhibit extreme hubris, or otherwise act in a way that invites divine retribution, they gain either Nemesis or Doom, proportional to how severe the transgression.

Nemesis is a die (in whatever system you use, likely a d20), that the GM keeps in reserve to use against you at a very inopportune time: an important Save, a crucial attack roll, a dangerous kill check, etc. This roll can be whatever the GM dictates (although it probably shouldn't generate critical hits). Nemesis inflicted for any particular act range from 1 to 5, depending on severity.

Nemesis dice never expire. They can be held onto and hoarded until a truly critical moment. The GM has discretion for what fate this entails. Nemesis can be removed by making amends with the offended god, by the various ways one might do so (material sacrifices, blood prices, donating to charity, self-flagellation, etc.). Or, Nemesis can be removed by getting another god to get the offended one off your back. The champions of gods in this way are like the international diplomats of the religious world. They have a certain amount of immunity before they're expelled.

The player-character find out how much Nemesis they have when they next sleep or long rest. It's not immediately apparent how much Nemesis a certain act has produced. Until this point, the GM cannot use Nemesis on that respective character.

Examples of acts that might produce Nemesis: 

• Killing someone. (Everyone's got a god. Maybe even if they attacked first. Do all the gods recognize a mortal's argument of self-defense? Probably not.)
• Touching a dead body. Maybe even looking at one. Maybe even mentioning a dead person's name.
• Cursing a god. Cursing The gods. Cursing God.
• Taking treasure from a place that has not been de-sanctified by a cleric.
• Beating up a priest, monk, druid, pilgrim, or other holy person.
• Killing a sacred stag, favored animal, or "monster" considered holy to a god (without the proper ritual beforehand).
• Supporting, being around, or being associated with somebody with active Nemesis. The closer you are, the more it radiates.
• Expressing hubris.

Doom is reserved for truly offensive acts in the eyes of the gods. Doom can never be removed by any means. Characters with Doom suffer the worst possible outcome on an injury table or death saving throw when next it is rolled (or at least something more severe than a potentially normal outcome). This can't be gamed (say, by trying to preempt it in a safe scenario). GM has discretion to withhold the Doom if the situation seems too safe.

Similar to Nemesis, Doom cannot be utilized or confirmed until an Omen has been revealed. It's up to the GM as to exactly when this happens. These should be specific to the offended god (e.g. a snake eating itself, a shattering mirror, an eclipse).

Examples of acts that might produce Doom:

• Defiling the altar of a death god.
• Hearing the banshee call your name.
• Slaughtering and looting a temple.
• Killing an (innocent) priest, monk, druid, or other holy person.
• Slaughtering the sacred chickens.

What's the Point?

What's the point of these mechanics? Well, maybe two things. One is that hopefully it might lead towards the campaign that emphasizes careful consideration of killing, particularly its religious consequences. Murder suddenly becomes a much more expensive proposition if the gods are paying attention to your violence. If you want to kill without consequence, you're going to need to get permission (or protection) from some gods.

So, what do you do instead of murder and plunder? Well, you can maybe murder and plunder only a little bit and maybe get a manageable amount of Nemesis. You can beat up or capture your enemies (but be careful with the priests!), or force them to run away. You can make sure that when you do kill and plunder, you've got some religious backing to do so.

Second, it really gets religion involved in the adventuring cycle. Want to do dungeon delving? Better consult a priest first. Get some blessings before you head out of town. Visit shrines along the way. Why are there unplundered shrines and treasures all over the place? Because most people know better than to mess with them. Going to fight some gnolls/orcs/trolls/etc.? Well, you'd better get some protection against their gods, or you've got some serious nemesis in store for you.