Wu Jen are an Arcane Spellcasting class present on the more Chinese flavors of Dungeons & Dragons. They combine the traditional Wizard spellcasting abilities with Chinese-flavored Elementalism (Earth, Water, Fire, Wood, Metal) and often have Monk-esque Ki Powers, but also have a lot of weird taboos that they must obey or else they lose access to their magic, kind of like Paladins, or pre-4th edition Druids, Barbarians and Monks.
Advanced Dungeons & Dragons (First Edition)
The Wu Jen appeared in First Edition AD&D in the Oriental Adventures by Gary Gygax. They were identical to Magic Users in the Players Handbook with the exception of Ki Powers that were gained as they advanced in level and a Taboo that must be selected at 1st level. Violating this taboo resulted "in the loss of spells, illness, or other evil events" (Oriental Adventures, pg 26). Most taboos were related to issues of personal hygiene such as bathing or the cutting of hair.
An upgraded version of the Wu Jen for second edition AD&D was featured on page 54 of issue #229 of Dragon Magazine. This version of the Wu Jen, like its original counterpart, was essentially a sort of wizard-monk hybrid, using magic and martial arts training combined to serve as a rambunctious wu-shu style warrior-wizard.
The 2e Wu Jen class is available to any race that can take the Mage (generalist Wizard) class. Requiring Int 9 and Con 12 to join, its key attribute is Intelligence, with a +10% bonus to XP gain for Int 16 or higher. Wu Jen use the wizard THAC0 progression and experience tables, but can use all weapons, can use magic items (bar armor and shields) available to both wizards and warriors, receive 1d4+1 hit points at first level, and 1d6 hit points at each subsequent level.
Wu Jen cannot be combined with kits or multiclassing.
A Wu Jen chooses one of five elemental schools at character creation: Earth, Air, Fire, Water or Nature. A wu jen can only learn spells from that school, and only gains 1 spell per level when leveling up.
Unlike a normal wizard, wu jen don't need to memorize spells ala Vancian Casting. They can cast any spell they know, whenever they like - at the cost of taking thrice the spell's level in damage when they cast. And, as a side-effect of the processes that let them do this, they halve the effects of magical healing (rounding up).
They still have to obey taboos, gaining 1 at first level and another at "every level divisible by five". Failing to observe a taboo costs the wu jen the ability to cast spells for 2d4 days.
Wu jen Trance like elves instead of sleeping. At 6th level, they gain the ability to spend 1d6+2 hit points in order to bump up any one physical attribute by +1d 4 points for 2d4 rounds. They also use the Exceptional Strength rating for fighters. Boosting Constitution does not grant bonus hit points. This physical buff can be used once per round, so long as the wu jen has the hit points to spend.
At 10th level, a wu jen begins attracting 1d4 pupils, all 1st level wu jen.
Finally, at 12th level, at the cost of 1 hit point, a wu jen can leap up to 30' in any direction they choose.
D&D 3rd Edition
Mimicking its introduction to the realms of Dungeons & Dragons, the Wu Jen first appeared in 3.x in the Oriental Adventures D20 sourcebook, before getting reposted with maybe some cleaning up in the Complete Arcane book, alongside the Warlock and the Warmage.
The main tweak was the added focus on Wu Xing inspired elemental magic; Wu Jen had a very specific list of spells they could use, dividing them up into Universal, Earth, Fire, Metal, Water and Wood categories. This was important because at 6th level they got to pick one of the five elements for "Elemental Mastery", which meant they had +2 caster level with spells from that category (as well as from the Universal category).
Beyond that, their big thing was the ability to pick one spell every 3 levels and apply a "Spell Secret", permanently applying the effects of one specific metamagic trait (Enlarge, Extend, Still or Silent) to that spell whenever they cast it.
They still had to obey their taboos, but violating one just cut off their ability to cast spells for the rest of the day. Which was good, because they picked up one taboo at 1st level and then a new one each time they gained a Spell Secret. The silliness of these taboos was lampshaded in the book:
- Can't bathe
- Can't cut hair
- Can't eat meat
- Can't touch a dead body
- Can't drink alcohol
- Can't wear one or more specific colors
- Can't light a fire
- Can't sit facing a certain direction
- Must make a daily offering of some kind (food, flowers or incense most commonly) to spirit patrons
They have some unique spells that make them inclined to become Gish. These include Giant Size (Increases your size a lot) and Body Outside of Body (Create copies of you that can't cast spells or use magic items, but retain your martial skills).
Like Shugenja and Pathfinder's Witch, Wu Jen are Tier 2 despite being prepared casters. This is because their spell list, which isn't really expanded elsewhere, lacks enough potent spells to trivialize everything, even if you know its coming.
There's no specific Wu Jen class in Pathfinder, but one could probably pull it off by taking one of the five Wu Xing-appropriate Elementalist archetypes (Earth, Fire, Water, Metal, Wood) and giving it some more Chinese flavor.
D&D 5th Edition
The Wu Jen reappeared in 5th edition as one of the six subclasses presented for the full Mystic class in Unearthed Arcana, which appeared on March 13 2017. Like most of its fellows, the 5e Wu Jen is ultimately based on one of the original AD&D schools of psionics - specifically, the Psychokinesis school, using psionic magic to manipulate the various elements. This is represented both by its list of associated Disciplines and by its class features, with the former directly manipulating various elements and the latter boosting its ability to interact with the elements both offensively and defensively.
At first level, it gains 2 additional Disciplines taken from the Wu Jen List - an array consisting of Mastery of Air, Fire, Force, Ice, Light & Darkness, Water, Weather, and Wood & Earth - as well as free proficiency in any two skills from a list consisting of Animal Handling, Arcana, History, Insight, Medicine, Nature, Perception, Religion, or Survival.
At 3rd level, it gains the Elemental Attunement feature. Essentially, if you haven't maxed out your psi limit, you can spend an extra psi point to ignore damage resistance when making an elemental psionic attack.
At 6th level, in a mythology gag to its origins as a Wizard variant, its Arcane Dabbler feature lets it take up to three 1st, 2nd or 3rd level wizard spells. It can fuel these by burning psi points to equate to spell slots; 2 points for a 1st level slot, 3 points for a 2nd level slot, 5 points for a 3rd level slot, 6 points for a 4th level slot, and maxing out at 7 points for a 5th level slot.
Finally, it finishes off its unique class features with Elemental Mastery, where it can boost a damage resistance it has to damage immunity for a turn by spending 2 psi points in reaction to taking damage of the appropriate type.
Like all Psychic Discplines in the mk3 Mystic, the Wu Jen's elemental masteries have a simple set of rules: each has a singular passive bonus which a wu jen can gain by choosing that discipline as a Psychic Focus, which they can only have one of at a time. It then consists of a small band of powers that a wu jen can activate by spending psionic energy points, or "psi points" for short.
Mastery of Air comes with a Focus ability that makes you immune to falling damage and which lets you ignore difficult terrain whilst walking. It has two powers with variable psi costs; Wind Step and Wind Stream. Both cost from 1-7 psi, with Wind Step letting you fly 20 feet per psi spent, and Wind Stream creating a line-shaped blast of air (30ft long, 5ft wide) that does 1d8 bludgeoning damage per psi spent and which can knock victims prone on a failed Strength save. Its other powers are all concentration effects. Cloak of Air costs 3 psi and can last up to 10 minutes, imposing disadvantage on attack rolls against you and letting you force enemies that flub a melee attack against you to reroll that attack against themselves. Wind Form, which costs 5 psi and lasts 10 minutes, grants you a flying speed of 60 feet. Misty Form (6 psi, 1 minute) is basically the Mist Form spell. Animate Air (7 psi, 1 hour) lets you conjure a loyal air elemental to do your bidding.
Mastery of Fire is, well, what are you expecting? Its Psychic Focus bonus is a nice little one-two combination of Resistance to Fire damage for yourself and a +2 damage bonus with your fire attacks. Which is handy because that's literally what this discipline is all about. Combustion is a concentration attack that literally lets you set somebody on fire with your brain, potentially inflicting 1d10 to 7d10 (depends how many of those 1-7 psi points you spend) fire damage and then burning them for 1d6 fire damage per round for up to 1 minute. Rolling Flame lets you drench a 20ft by 20ft cube in flames and keep them burning there through concentration for up to a minute, all for a measly 3 psi. Detonation, costing 5 psi, is basically a psychokinetic fireball attack. Fire Form, another 5 psi power, is a concentration power that lets you cloak yourself in flames that burn everything around you for up to a minute. Finally, Animate Fire lets you burn 7 psi in a potentially hour-long concentration power that creates a fire elemental.
Mastery of Force is about pure psychokinetic prowess; this is your telekinesis style, and it throws around Force damage like it's going out of style. Psychic Focus grants you Advantage on Strength checks, whilst its powers consist of Push and Move, which are basic potentially deadly telekinetic manipulation; Inertial Armor, which is a mage armor effect that costs 2 psi; Telekinetic Barrier, which costs 3 psi to create a concentration (10 mins) wall of force; and Grasp, which costs 3 psi and is a concentration (1 min) telekinetic grapple, which you can also use to crush or move your victim.
Mastery of Ice is, obviously, the frosty counterpart to Mastery of Fire. Using this as your Psychic Focus gives you Resistance to Cold Damage (duh). Ice Spike is a 120ft ranged attack that costs 1-7 psi; on a hit, it does 1d8 Cold damage per psi and slows the target until the sart of your next turn - if they pass a Dexterity save, they halve the damage and aren't slowed. Ice Sheet costs 2 psi and creates a 20ft wide ice slick at a spot of your choosing within 60 feet, lasting for 10 minutes. Frozen Sanctuary lets you gain 20 temporary HP by burning 3 psi. Frozen Rain is a nastier version of ice storm; it costs 5 psi, is a 1 minute Concentration effect, and affects a 20ft sphere within 120 feet, causing all critters within to make a Constitution save - if they fail, they take 6d6 Cold damage (+1d6 per bonus psi point you spend) and are reduced to Speed 0 until your Concentration ends, whilst success halves the damage and nullifies the slowing effect. A creature slowed by Frozen Rain can spend an action to make a Strength (Athletics) check against this power's save DC; success restores mobility. Finally, Ice Barrier basically lets the wu jen cast Wall of Ice for 6 psi with a Concentration of 10 minutes.
Mastery of Light and Darkness would be called "photokinesis" in more sci-fi settings. It lets you manipulate light and dark, as you can probably guess. When engaged as a Psionic Focus, you have Magical Darkvision 30 feet, which allows you to ignore even magical darkness. Its Darkness power is basically the same as the Darkness spell, but costs 1-7 psi, and affects a sphere (10ft per psi point spent) within 60 feet. Light costs 2 psi and is a 1 minute long Concentration effect, but basically lets you turn an object or a person into a glowing torch. Shadow Beasts lets you summon 2 shadows as a Concentration power for 1 minute at a cost of 3 psi. Finally, Radiant Beam lets you blast a creature within 60 feet with a psionic laser for 5 psi. The target must pass a Dexterity save or take 6d6 Radiant damage and be blinded; their blindness is a Concentration effect for you, and can last up to 1 minute, but they can make a save to end the blindness at the end of each turn. On a successful save, they take half damage and aren't blinded. You can boost the radiant damage that this beam inflicts by +1d6 per bonus psi point.
Mastery of Water is another obvious elemental psionic school. As your Psychic Focus, you have a Swim speed equal to your walking speed and the ability to breathe water. Dessicate lets you spend 1-7 psi to inflict 1d10 Necrotic damage per psi spent on a creature within 60 feet, half that if they pass a Constitution saving throw. Watery Grasp lets you spend 2 psi to create a wave that knocks people off of their feet and drags them closer. Water Whip is basically the same as the Monk ki power of the same name, costing 3 psi. Water Breathing lets you grant yourself and up to 10 willing allies the ability to breathe underwater for the nex 24 hours, all at the cost of 5 psi. Water Sphere lets you entrap a creature in a bubble of solid water as a 1 minute Concentration effect by spending 6 psi. Finally, like the other "classic elemental" psionic schools, you have the Animate Water psi power; spend 7 psi and get a pet Water Elemental as a Concentration effect that lasts 1 hour.
Mastery of Weather is basically Mastery of Air, but with more zappy powers. As your Psychic Focus, you gain Resistance to Lightning & Thunder damage. Cloud Steps lets you summon a spiraling staircase of solid clouds for 1-7 psi that reaches 20 feet up per psi spent; this is a Concentration effect that lasts 10 minutes. Hungry Lightning is basically a Lightning Bolt spell; it costs 1-7 psi and does 1d8 lightning damage per psi spent, or half that if the victim saves. Wall of Clouds lets you burn 2 psi to create... well, waht do you think? It's a Concentration effect that lasts 2 minutes, and it only blocks vision, not physical bodies. Whirlwind costs 2 psi and summons a howling 20ft sphere of wind within 60 feet. Lightning Leap lets you spend 5 psi to create a 60ft long 5ft wide line of lightning that not only inflicts 6d6 lightning damage on anything in its path that fails a Dexterity save (+1d6 per bonus psi spent, but half the damage if they save), but also lets you teleport to an unoccupied space touched by the line. Wall of Thunder costs 6 psi and is a Concentration effect that lasts for 10 minutes; it's not only difficult lterrain to try and get through it, but anything trying has to pass a Strength save or take 6d6 Thunder damage and be thrown backwards 30 feet. Finally, Thunder Clap lets you spend 7 psi to target a 20ft sphere within 60 feet; anything in this sphere that fails a Constitution save takes 8d6 Thunder damage and is Stunned until the end of your next turn.
Mastery of Wood and Earth folds geokinesis and plant control into one discipline. As your Psychic Focus, it grants you +1 AC. Animate Weapon lets you spend 1-7 psi to telekinetically launch your one-handed melee weapon at a target within 30 feet and make an attack that does +1d10 force damage per psi spent. Warp Weapon lets you spend 2 psi to try and mangle a nonmagical weapon your opponent is holding, rendering it useless until the end of your next turn. Warp Armor costs 3 psi and similarly lets you try and mess over a foe's suit of non-magical armor. Wall of Wood lets you conjure a solid wall of wood for 3 psi, which is a Concentration effect that lasts 1 hour. Armored Form costs 6 psi and is a 1 minute Concentration effect, but it grants you Resistance to Physical Attacks whilst it lasts. Finally, Animate Earth is your "summon an earth elemental" power; 7 psi, Concentration, lasts 1 hour.