Water Bender, Variant (5e Class)
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The tiefling manipulates the water out of his waterskin to intercept the bandit’s sword. He rips the sword out of the bandit’s hands and gives him a nasty cut with his own blade.
A kind-looking gnome woman bends water around her hands, which glow with a healing light. She gently touches her ally’s wounds, which begin to heal rapidly.
A human gathers water from the air and flings it out as the small water droplets form into tiny icicles that pierce the surrounding enemy.
Water Benders have the natural ability to manipulate water to their will. Their techniques often use their opponent’s force against them, which leads to a more defensive fighting style. Although they may not always have their element around them like the other three elements, they make up for it with very clever techniques to gather the water they need to defend themselves.
Water Benders draw upon the idea of change when they bend, similar to how water is rarely still, always changing. The first Water Benders learned how to control water by studying the moon and how it affected the tides. Most Water Bending forms mimic the constant ebbing and flowing motions that water makes. Water Bending movement generally involve smooth motions with the arms and legs that move with the water, the exception being Swamp Water Bending style, which uses very stiff arm positioning.
Raising and Training
Most Water Benders come from either the Southern or Northern Water Tribe. Each of these tribes exist on one of the poles of the earth, which sometimes results in harsh living conditions. Some Water Benders can be found from swamps as well.
The Water Nation is known for having a strong sense of family and community. The people in both tribes and even the swamp dwellers tend to live very close to one another, and strive to help support their family as well as the tribe.
For a Water Bender to become an adventurer, they would have to have a good reason to leave their tribe. Perhaps their tribe was attacked, and they are trying to track down the attackers. Maybe they were out on a fishing boat, when they were captured and later escaped from a group of pirates.
Creating a Water Bender
As you make your Water Bender, think about how you grew up in one of the Water Tribes and learned your Water Bending. Were you taught more combat Water Bending or more of the healing style? Did you grow up with that strong sense of family? Do you appreciate the tribe that you grew up in?
Consider why you left. Did you decide to make a journey across the world to see the other Water Tribe? Do you wish to experience all variations of Water Bending? Do you not believe in the Water Tribe’s “family” style of living?
Most Water Benders lean towards a Lawful alignment because of the family values instilled in them from their tribe. Whether they be good or evil may depend on the family in question.
- Quick Build
You can make an Water Bender quickly by following these suggestions. First, make Wisdom your highest ability score, followed by Dexterity. Second, choose the sailor background.
As a Water Bender you gain the following class features.
- Hit Points
Weapons: Simple weapons
Tools: Choose Fishing Tackle or Healer's Kit
Saving Throws: Wisdom, Constitution
Skills: Choose two from Animal Handling, Medicine, Insight, Investigation, Perception, and Survival
You start with the following equipment, in addition to the equipment granted by your background:
- a spear
- (a) Fishing Tackle or (b) Healer's Kit
- (a) Dungeoneer’s Pack or (b) Explorer's Pack
- a hunting trap and a hooded lantern
|Restrain Time||Chi Points||Critical Heal Die||Basic/Advanced||Tehnique Level||Features|
|1st||+2||1 round||-||0||-||-||Fluid Defense, Elemental Arts|
|2nd||+2||1 round||4||0||-||-||Chi, Slipless Grip|
|3rd||+2||1 round||5||0||1/3||1-2||Momentous Movement, Water Bending Techniques|
|4th||+2||1 round||6||0||1/4||1-2||Ability Score Improvement, Icy Ramp|
|5th||+3||2 rounds||7||d6||1/5||1-3||Extra Attack, Instant Water Healing, Critical Heal|
|6th||+3||2 rounds||8||d6||2/6||1-3||Technique Feature|
|7th||+3||2 rounds||9||d6||2/7||1-4||Momentous Movement Upgrade|
|8th||+3||2 rounds||10||d8||2/8||1-4||Ability Score Improvement|
|9th||+4||2 rounds||11||d8||2/9||1-5||Watery Limbs (1)|
|10th||+4||2 rounds||12||d8||2/10||1-5||Healing Upgrade|
|12th||+4||3 rounds||14||d10||3/12||1-6||Ability Score Improvement|
|13th||+5||3 rounds||15||d10||3/13||1-7||Medical Eye/Cool Breath|
|14th||+5||3 rounds||16||d10||3/14||1-7||Elemental Weapon, Watery Limbs (2)|
|15th||+5||3 rounds||17||d10||3/15||1-8||Plant Bending|
|16th||+5||3 rounds||18||d12||3/16||1-8||Ability Score Improvement|
|17th||+6||4 rounds||19||d12||4/17||1-9||Watery Limbs (3)|
|18th||+6||4 rounds||20||d12||4/18||1-9||Octopus Form|
|19th||+6||4 rounds||21||d12||4/18||1-9||Ability Score Improvement|
|20th||+6||4 rounds||22||d20||5/18||1-9||Blood Bending, Watery Limbs (4)|
IMPORTANT NOTE: Most of these abilities require you to have water with you. Keep that in mind.
Beginning at 1st level, while you are wearing no armor and not wielding a shield, your AC equals 10 + your Dexterity modifier + your Wisdom modifier.
At 1st level, your practice of bending arts has earned you some special abilities.
You can use Dexterity instead of Strength for attack and damage rolls when making an attack you are proficient in.
When you hit a creature within 5 ft. of you with an Advanced Technique of level 1 or higher or attack an enemy with a melee attack, you can take a bonus action to freeze your target’s feet in ice. This last for 1 round. The time this effect lasts increases as you level up, which you can see in the Restrain Time column of the Water Bender table. The target can also attempt to make a Strength Saving throw against your Bending Save DC, which is calculated further down this page, to break out of the ice as an action on their turn.
You know the cantrip shape water.
At 2nd level, you can start using more advanced Water Bending techniques. The amount of energy that you have is measured by your number of chi points. Your Water Bender level determines the number of points you have, as shown in the Chi Points column of the Water Bender table. You regain all used chi points after a short or long rest.
You can spend chi points to fuel various Water Bending features. You start knowing three such features: Healing Water, Water Run, and Air Hydration. You learn more Water Bending features as you level up.
When you spend a chi point, it is unavailable until you finish a short or long rest, at the end of which you draw all of your expended chi back into yourself. You must spend at least 30 minutes of the rest meditating to regain your chi points.
Some of the Water Bending features require you to make a ranged spell attack to hit your target or your target to make a saving throw to resist the feature’s effect. The bending attack bonus and save DC are calculated as follows:
- Bending Abilities
Dexterity and Wisdom are your bending abilities for your Water Bender features and techniques. You move as swift as rapids, and have a head as cool as ice. You use Dexterity and Wisdom whenever an Water Bender feature or technique refers to your bending ability. In addition, you use your Dexterity and Wisdom modifiers when setting the saving throw DC for a Water Bender feature or technique you use and when making an attack roll with a feature.
- Bending Ability Modifier
Your bending ability modifier is equal to your wisdom modifier.
- Bending Attack Bonus
Proficiency bonus + Bending ability modifier
- Save DC
Bending Attack Bonus + 8
Here are your first three Water Bending features:
- Healing Water
When out of combat, you surround your hands with water and cast Cure Wounds at its base level once per short/long rest.
- Water Run
You can cause water to solidify just enough for you to run across it as a bonus action at the cost of 1 chi point. You cannot end a turn while over the water, or you will begin to sink. This effect lasts for 1 hour. When running on the water, it is a concentration spell. You can use this ability with 2 chi points so that you can end your turn while over water and not sink.
- Air Hydration
As a bonus action, you can consume 1 chi point to gather water from the air, from surrounding plants, from sweat or moisture on other objects. This is enough water to fill a quarter of a water skin, or 1 pint. Extra chi points result in extra pints gathered. If the area is incredibly dry or incredibly moist, it is up to the DM to determine how much water is gathered per chi point.
Starting at 2nd level, when walking or climbing on an icy or slick surface due to water, you take on no disadvantage or penalty. You can use your reaction to give one other creature this benefit that is within 15 feet of you as they move through the slippery terrain.
Starting at 3rd level, when an opponent hits you with a melee attack, you can use your reaction to consume 1 chi point to attempt to grasp the attacker with water and carry their momentum to affect them in some way. This does not apply to critical hits. You must make a Dexterity saving throw against their accuracy. A failure results in taking half damage. A success results in no damage and bending water around the attacker’s hands and choosing one of the following effects to occur:
You cause the water to freeze around the attacker’s hands. Their hands are considered petrified, so they cannot release their weapon whatsoever. Their attacks now have disadvantage. This lasts for 1 minute or until they smash the ice, which requires the target to make a Strength saving throw that beats your Save DC, or they break through the ice.
You can use the water to push or pull the target a set number of feet in any direction. If they are one size larger than you, you can push/pull them up to 5 feet. If they are any larger than that, you cannot affect them. If they are of equal size to you, you can push/pull them up to 10 feet. Creatures 1 size smaller than you can be pushed or pulled 15 feet, 2 sizes smaller 25 feet, etc. The target is prone after being thrown.
You can use the water to rip the weapon out of the attacker’s hands, if they are using one. You can toss it up to 30 feet away, not dealing any damage when thrown.
Water Bending Techniques
Starting at the 3rd level, you can have up to 3 Advanced Water Bending Techniques of level 1-2 and 1 Basic Water Bending Technique from the Water Technique list. To use an Advanced Technique requires you to consume a number of chi points equal to the technique’s level. Basic techniques require no chi points.
As you gain levels in this class, you will be able to learn higher level techniques, as seen on the Technique Level column of the Water Bender table, as well as have more techniques prepared, as seen on the Basic/Advanced column of the Water Bender table.
Additionally, when you gain a level in this class, you can choose one of the Advanced or Basic techniques you know and replace it with another Advanced or Basic technique from the Water Technique list, which also must be of a level for which you are capable of.
The only material you need is enough water that the DM deems necessary to do the technique. Every technique has the "S" component, and none have the “V” component.
Water Bending Sub-Types
Water benders can be found all over the world, and as such, many different techniques have been learned, which utilize different aspects of water, the main three, however, are the styles from the Northern and Southern Poles, and the Foggy Swamp style, your character history will largely determine what style you choose. You gain new abilities from the techniques at 3rd, 6th, 11th and 17th level, and all the abilities are detailed at the end of the class description.
Ability Score Increase
When you reach 4th level, and again at 8th, 12th, 16th and 19th level, you can increase one ability score of your choice by 2, or you can increase two ability scores of your choice by 1. As normal, you can't increase an ability score above 20 using this feature.
Using the optional feats rule, you can forgo taking this feature to take a feat of your choice instead.
Staring at 4th level, when falling, you can use 1 chi point as a reaction to bend water to create an ice ramp to break your fall and slide down. The DM will determine if you have enough water on/around you to create a long enough ramp. Anyone else that happens to go down the ramp, unless they are also Water Benders, must make a Dex saving throw of DC 10 to avoid damage and stay upright, on a fail, they take half damage (calculated through basic fall damage rules) and fall off the ramp, rendering them prone. Your movement isn’t used as you go down the ramp. You can also use this on a creature or object that is falling within 30 feet of you.
Beginning at 5th level, you can attack twice, instead of once, whenever you take the Attack action on your turn.
Starting at 5th level, when trying to stabilize a creature, if you roll a natural 15 or higher on your d20, you can cause yourself or one creature within 5 feet of you to gain a number of health points equal to your Critical Heal die, which can be found in the Critical Heal Die column of the Water Bender table, plus your Wisdom modifier. This can be used once per short/long rest.
Starting at 6th level, once per short or long rest, you can alter the temperature of the water in the air and create something akin to a modified version of the Fog Cloud spell. This version only requires somatic components, and doesn't require concentration to be maintained. The initial creation of the cloud doesn't require any chi points, but using it at higher levels requires one chi point per additional level, up to 10 points as a maximum. Additionally, as an action and at the cost of 1 chi point, you can move the cloud up to 30ft in any direction. At 15th level, this can be used twice per short or long rest.
Momentous Movement Upgrade
Starting at 7th level, Momentous Movement can now apply to critical hits. Also, all of the effects of this ability improve:
- Lasts for 5 minutes out of combat, and 1 minute in combat, and can be melted by any means that the DM deems appropriate.
- You can push/pull the target an additional 5 feet, you can use this on a creature 2 sizes larger than you, but never gargantuan, and throwing the target at another enemy forces the enemy to make a Dexterity saving throw against your Save DC. On a failure, both targets take 1d8 times the size of the creature being thrown of bludgeoning damage. The thrown enemy is knocked prone.
Tiny = 1/4 (rounded up)
Small = 1/2 (rounded up)
Medium = 1
Large = 2
Huge = 3
For example, if you threw a large creature at another creature, they would both receive 1d8 x 2 bludgeoning damage.
- As you disarm your opponent, you can now bring the weapon that they were holding to yourself and equip it, ready to be used as a weapon at the beginning of the next turn. You are proficient when wielding a weapon like this. You can continue fighting with this weapon in subsequent turns, using an action to attack. While you fight with this weapon using this feature, you cannot disarm another creature with this feature.
Starting at 9th level, you can wrap water around your arms as a bonus action, giving your melee attacks more range and power. Your range increases to 15 feet and the damage dealt increases by 1d6. This increases at level 14 (1d8), level 17 (2d6) and level 20 (2d8). This buff lasts for 5 minutes.
Starting at 10th level, all of your healing abilities can have the possibility of curing any and all negative physical effects at once. This includes poison, disease, paralysis, blindness, petrification and being deafened. When you heal, you can choose to consume 1 extra chi point to make a Medicine check. The DC of curing any one of these effeccts is 15. For every extra effect, the DC increases by 5. For example, if you used Healing Water on a target who was both blind and paralyzed, the DC to cure both conditions would be 20. If you rolled a 15-19, the DM would randomly choose one of the conditions to be cured, but not the other.
Starting at 13th level, you have learned to study people to tell if they’re feeling sick and need care, or just hoping to get some attention. You gain proficiency in Medicine and Insight. If you already have proficiency in one or both of these skills, you gain double proficiency.
Starting at 13th level, you can use an action and consume 3 chi points to freeze a creature or object within 60 feet of you. The condition is that you must have attacked this opponent with a water attack beforehand or that they have plenty of water on them. You breathe a cold breath as the water on their body freezes up in seconds. The target's frozen body is considered petrified until the ice is broken (Strength saving throw against a DC of 10+wis mod+1/8th of water damage dealt to the enemy) or melted (which takes one hour under normal circumstances).
Starting at 14th level, as a bonus action, you can expend 5 chi points to create a spear out of water or ice. This spear has a range of 10 feet and a throwing range of 30/70. You can land a critical hit with this weapon by rolling a 19 or a 20. When attacking with this weapon, you can expend chi points to either increase accuracy rolls, damage rolls, or range. Increasing accuracy rolls to or above 19 does not cause a critical hit. 1 chi point results in an increase of 1 to the roll or an increase of 5 feet to the range. The damage and range increase is only for the one attack. The weapon does not permanently gain this buff. This weapon lasts for 10 minutes.
Starting at 15th level, you have honed your waterbending enough for you to bend the water that exists inside of plants. You can cause these effects to happen when bending plants that are within 100 feet of you:
- If the plant has vines or any sort of long appendages, you can bend them as an action and consuming 2 chi points to attempt to grab an object or opponent. The target must succeed a Dex saving throw or be grabbed and restrained. The DM determines how far you can reach with any given plant. If you want to throw the target, you can do so in the same action and it follows the same damage and distance rules as Momentous Movement’s Yank effect, with the distance possibly changing depending on the plant. If you just want to continue to restrain the target, at the beginning of each of the target’s turns, they can make a Strength saving throw as an action to break out of the grip.
- You can pull vines and plants around you as an action and a varying amount of chi points to create plant armor. It’s up to the DM to determine how much your AC is increased based on the plants you bend. The amount of chi points consumed is equal to the amount your AC increases. Certain plants may also grant you certain resistances. Almost all plants can be destroyed by fire-based attacks. This is considered a concentration spell for up to 5 minutes.
- You rip the water out of the plant as a bonus action and consuming 1 chi point, allowing you to use it with your normal water abilities and killing the plant. It’s up to the DM to determine how much water you get.
If the plant is alive, it must make a Constitution saving throw. If it is at night, the plant has disadvantage. If it is during the full moon, it is guaranteed to fail the saving throw. (DM, be fair about when there is or isn’t a full moon. Keep literal track of the days that pass in game and the different moon positions if you have to.) The waterbender can use this living plant as a puppet instead if the plant fails the saving throw. If the waterbender is ever hurt while still in control of a plant, the plant can attempt another saving throw to break free of the Water Bender’s control. You can use a bonus action to move the target up to 30 feet, or you can have them attack with any weapon they have on them or is within their reach. You roll for attack and damage, and you are proficient with any weapon.
Starting at 18th level, you have learned the defensive Octopus Form. By consuming your action and 5 chi points, you create a ring of water around you with many tendrils. This acts as a concentration spell. The circle has a radius of 15 feet centered on you. The size of the circle or cost of chi points may vary depending on the amount of water available (Up to DM). You cannot move this circle once you have created it, and if you step out of it, the form falls apart. Your AC increases by 7 when enemies attack from outside of the ring and by 3 when they are inside of the ring, and all ranged attacks have disadvantage against you. When an opponent walks through the ring of water, they must make a Dex saving throw with disadvantage against your Save DC. Success results in them getting through, while failure results in a tentacle grabbing them and throwing them a maximum of 15 feet in any direction you choose. Throwing the target at another enemy has the same damage rules as Momentous Movement’s Yank effect. At the end of every enemy’s turn that is in the circle, they must make a Dex saving throw with advantage or be tossed out. You can use your action to make an attack to any enemy within 10 feet of the ring using. You would use your Bending Attack Bonus, and on a hit, you would deal 3d8 cold damage. You can also grab and throw anyone within 10 feet of the ring. The target must make a Dexterity Saving Throw against your Save DC to avoid being grabbed. Lastly, you could cause the ring to explode outward and have the effect of the last action of Investiture of Water, but in all directions up to 15 feet away. That last action causes the Octopus Form to fall apart.
At 20th level, you have perfected your waterbending so that you can feel and manipulate the blood that flows through every living thing. As an action and consuming 8 chi points, you can attempt to bend the blood in a creature's body who is within 60 feet of you, making them your puppet. The target must make a Constitution saving throw against your Save DC. If it is at night, it is with disadvantage. If it is during the full moon, the ability immediately succeeds. (DM, be fair about when there is or isn’t a full moon. Keep literal track of the days that pass in game and the different moon positions if you have to.) If a Water Bender tries to Blood Bend another Water Bender, the targeted Water Bender has advantage on their saving throw all of the time, even during a full moon. A success results in resisting the Blood Bending, and a failure turns the target into the Water Bender’s puppet. This acts as a concentration spell. The target can still talk and has their own consciousness, but they cannot control the rest of their body at all. You can use a bonus action to move the target up to 30 feet, or you can have them attack with any weapon they have on them or is within their reach. You roll for attack and damage, and you are proficient with any weapon. Any time you are damaged or you do any Water Technique or use any Water Bender ability that isn’t concentration, the target can make another saving throw. This can be used on any creature that still has blood in their veins, whether it be animals, insects, or even the recently deceased. If they are dead, they automatically fail the saving throw.
Benders from the North Pole follow the most traditional, and most spiritual form of water bending. Characterized by slow, graceful movements, and fluid motions that mimic the water itself, North Pole benders are traditionally more versed in converting ice to water and vice versa, and in the healing properties of water. They are a spiritual people, and this is reflected in their style of bending.
Instant Water Healing
Starting at 3rd level, whenever you are touching water at least up to your knees, you can use your reaction to restore a number of hit points equal to 3 times your Water Bender Level plus your Wisdom modifier. You must complete a short or long rest before using this ability again.
Starting at 6th level, you can use a simple, offensive Water Bending attack for close-combat. As an attack, you bend ice at a target within 5 ft. of you, dealing 1d6 + Bending Modifier points of cold damage. You use your Bending Attack Bonus for this attack. This acts as a normal attack and consumes no Chi.
At 11th level, your water bending technique becomes more fluid, allowing you to use a technique that would usually be a full action as a bonus action. This ability can only be used an amount of times equal to half your bending attack modifier, rounded up (if necessary) per long rest. This ability cannot be used in the same turn as multi-attack.
At 17th level, your training with the art of healing has now reached its peak, when you and a group of allies are in water that is at least up to their knees, you can expend 10 chi points to restore up to 700 hit points, divided how you see fit among however many allies you wish to heal.
The people of the South Pole have had their bender population diminished severely, and as such, most of the people of the tribe are now trained in combat through weapons. Given that the Southern Water tribe has fewer benders, even those that can bend are also taught weapon skills such as spears, boomerangs, hatchets, and occasionally swords, as a result, even the few benders in the Southern Tribe are skilled in weapons combat.
Your younger life has been spent learning how to wield a select few weapons, and being able to survive in the harsh climate, gain proficiency in one melee martial weapon, and one ranged martial weapon, additionally gain proficiency in survival, if you already have proficiency, gain expertise.
Starting at 6th level, your precision in waterbending allows you to make weapons out of ice. You can spend 2 chi points to craft a simple melee weapon or 4 points for a martial melee weapon. The weapon does an extra 1d6+ half your level in cold damage.
Your training as a hunter has made you familiar with the frigid environment around you. Starting at 11th level, you gain all the bonuses of a ranger's "natural explorer" ability when you're in terrain that is predominantly ice and snow.
In addition, you have advantage against all checks related to being surprised, regardless of terrain, while you're awake, by non-magical means, and you have advantage on all perception and investigation checks. These checks are considered to automatically succeed if in icy, snowy or the correct (according to the DM's opinion) terrain.
Starting at 17th level, your skills in combat become battle hardened, and you can now read your opponents moves as easily as a wizard reading a tome. You gain the following abilities:
-Tuck and Roll: When you are subjected to an effect, such as a red dragon’s fiery breath or a lightning bolt spell, that allows you to make a Dexterity saving throw to take only half damage, you instead take no damage if you succeed on the saving throw, and only half damage if you fail.
-Flowing Redirection: When a hostile creature misses you with a melee attack, you can use your reaction to force that creature to repeat the same attack against another creature (other than itself) of your choice within ten feet of the enemy.
-Lesser Uncanny Dodge: Once per long or short rest, when an attacker that you can see hits you with an attack, you can use your reaction to halve the attack’s damage against you.
Foggy Swamp Style
The swamp benders are one of the only "organized" bending groups in the Earth Kingdom, located in the Foggy Swamp, in the Southwestern area of the Earth Kingdom. Their style is much more rigid than that of the poles benders, likely reflecting the stagnation of the water they inhabit. Their techniques have been designed through the need to catch prey, and navigate the tough swamp habitat, and as such, are more reliant on manipulating plants, navigation, and stealth.
Connected With Nature
Swamp benders tend to have more of a connection to plants and nature than their cold climate counterparts. At 3rd level, you have advantage on Perception (Wisdom) checks while in nature or rural environments. You can also move through difficult terrain caused by plants at normal speed.
Starting at 6th level, your time in the swamp has allowed you to effortlessly combine dirt and water. As an attack, you bend mud at a target within 10 ft. of you, dealing 1d6 + Bending Modifier points of damage. You use your Bending Attack Bonus for this attack. This acts as a normal attack and consumes no Chi.
At 11th level, you can spend 2 extra chi points while using your water bending techniques to fill the water with swamp-dwelling microbes. Any creature that is attacked with your water bending technique must make a Constitution save equal to 10+ your wisdom modifier + your dexterity. On a failed save, the target takes an additional 2d6 poison damage and is poisoned.
Guardian of the Swamp
At 17th level, you can control the water in the surrounding plant life and call it to your aid. You can spend 8 ki point to create plant armor around your body to deal nature's judgment. You have stats of a shambling mound and can use your weapons and skills while using this form. If you are dropped to 0 hit points while using this form, you revert back to your original form.
Water Technique List
Note: All healing techniques require that you are touching the water and the water is touching the creature you are healing.
Elemental Blast (cold damage only)
Elemental Blow (cold damage only)
Elemental Edge (cold damage only)
- 1st Level
Purify Food and Drink (only liquid poisons)
- 2nd Level
- 3rd Level
Water Breathing (concentration)
- 4th Level
Greater Restoration (normally a 5th level spell, but this version cannot cure curses.)
- 5th Level
- 6th Level
- 7th Level
- 8th Level
- 9th Level
The player can attempt to think of their own Water Bending technique if they so choose. It is up to the DM to determine (a) if the Water Bender is at a high enough level to accomplish this technique and (b) how many ki points it would cost, as well as casting time (action, bonus action, etc.) A suggestion to the DM for making this decisions would be to look at the Water Spells and abilities the Water Bender already has at this level and compare them to the technique the player wants to create. If you think the custom technique is stronger than what they are currently capable of, you reject the idea, or cause a nasty side effect to occur if they attempt this technique, if you think it's only a little bit outside of their skill level. You could also force them to roll a check or saving throw of some sort to see if they are successful at doing the technique or not. A custom technique takes up 1 spell in the player's Water Spell list.
Prerequisites. To qualify for multiclassing into the Water Bending class, you must meet these prerequisites: you cannot be a bender of another element, and you have to either have some sort of Water Nation ancestry, or Harmonic Convergence happens (Explanation of Harmonic Convergence) and you gain Water Bending. Talk to your DM to make it work.