Mechanics

A lot of the campaign's core game mechanics are homebrewed so this article will tackle on the different things to look out for. There are many similarities with classic DnD. Most homebrew mechanics were inspired by ATLA.

Following the Combat Trends of ATLA

Many opponents are easily defeated in one to two hits

Full strikes deal tons of damage, often around half of a target's HP. This is because in this battle system, there are generally many options to escape hits and avoid damage. This means that hitting or getting hit is a big deal. Assiting allies in hitting opponents is key to victory in combat.

Most moves in a class' kit are bare-bones

The biggest limit to someone's creativity during an action is how much material they can handle (or in the case of Martials, how limited their weapons and bodies are). Creativity is highly encouraged, as long as it stays within the alloted capabilties of a single action/turn (to be discussed later)

Damage type is dependant on how the action is performed

Your moves deal different types of damage depending on how its used. Sharp ice shards will deal piercing and hard rocks will deal bludgeoning.

Assisting an ally helps lower the DC of moves

If you restrict a target's movement, then it makes hitting the target a lot easier for everyone else. Another example would be bending an entire stone building, together with other earthbenders. Actions of insane magnitudes can be achieved if many individuals help out.

Stamina

Almost all moves cost stamina to perform. The bigger the move, the more stamina it consumes. Some moves can consume stamina points to become stronger. This is dependent on what class or classes you pick.
Most builds start with a standard maximum stamina of 30.

What To Do in a Single Turn

During your turn, you may do any and all of the following, in any order.

Action

This is how you do standard activities with limited restrictions. Most damage rolls come from Actions. For benders, this is where you are allowed to bend huge amounts of material. For martials, this is where they deal the most damage. You only get 1 action per turn.

Bonus Action

This is very similar to Actions, except of its restrictions. This is where you can do additional things that will not deal additional damage (except firebenders). You can grapple, propel, create, etc. Bonus actions are limited to the small amount of material that you are allowed to bend. You get 1 bonus action per turn.

Fun fact

Firebenders are the only class that can damage opponents using their bonus action. This is quite limited in its range and damage but sometimes, every bit helps.

Movement

Using your movement speed, you can position yourself across the terrain. Every 5 feet of movement you make consumes 5 feet from your available movement speed. If you have flight speed or swim speed, every 5 feet of movement substracts 5 feet of movement to all types of movement speed. Most builds have a standard movement speed of 30 feet. You may use your movement before and after an action and/or bonus action.

Dialogue

To encourage roleplay during combat, dialogue does not use up an action nor a bonus action. It can be done at any point within anyone's turn. Feel free to persuade or decieve. Just don't take too much time off other players' turns.

Reactions

Reactions are a precious resource that each person should spend wisely. They allow you to interrupt and respond to any action, bonus action, movement, dialogue and other reactions that another person/entity is currently doing. Reactions cost more stamina.

Capabilities of Reactions

Reactions are just actions that are forced into the moment, even if it is outside of your turn. This means you have access to most of your moveset when reacting. Here are some examples of what you could do:

Shield yourself from an incoming attack using bending

Dodge an action so that it misses you (ignores roll to hit)

Assist an ally with their attack (so that it hits)

Synergize with an ally, to do something before or after their move

Disable or hinder the opponent

Attack (if your reaction to an attack is another attack, both attacks push through)

Number of Reactions

Each player gets 1 reaction every turn to spend at any time. This reaction refreshes at the start of your turn.

Limitations of Reactions

You cannot react to the same combat interaction/scenario. This means that you cannot react twice within a single moment.

Example Combat Scenario

1. Opponent starts an attack
2. You react by creating a barrier of water
3. The same opponent reacts to the barrier, by burning the barrier

All of this happens within a single moment/chain of events. You cannot force another reaction upon the same chain of events. The chain must resolve before you can react again.
As a general tip, make sure your reaction is impactful enough because your reactions may also be interrupted by another reaction.

Health

Reaching 0 HP forces you to make death saves at the start of your turn. Succeeding 3 death saves stabilizes your character, though you are still essentially unconcious, meaning you still wont be able to fight.
Healing a target automatically stabilizes that target. However, this target would still unable to fight.
Getting a natural 20 (or a crit) in a death save or heal puts your character back up to 1 HP, making them conscious again and able to do actions.

Aura

Any material within 30 feet of you can be bended by you as long as you have line of sight. The material can still be bended even after it leaves your aura range, if you were the one who bends the material out of your aura.
An example is if you reach a piece of rock that is 30 feet from you and bend it towards the enemy 50 feet away. You bend the rock with 20 feet of range.

Targeting Specific Body Parts

When attacking opponents, you have the option to target a specific part of the body. However this increases the DC (or AC) of the attack.
This means that going for the eyes, ears, or balls of the opponent may decrease the chances of hitting them, rather than hitting them normally. Hitting certain body parts does bring certain debuffs.

Short Rest

During a short rest, do the following:

Recover 2d10 HP (if you are not knocked out)

Reroll any rolls that are 3 or lower

Add your CON modifier to the roll

Recover 10 + d10 stamina

Reroll any rolls that are 2 or lower

If knocked out and treated by a healer, gain consciousness again and receive 10 HP

Long Rest

During a long rest, do the following:

Recover all your HP

Recover all your stamina

If knocked out, gain consciousness again