HxH

ITT: come up with an interesting and original Nen ability that isn't broken.

Anything can be broken.

Manipulator. Contract, can only use it on one person. The ability to make Killua my sex slave forever.

Yeah, but if it's an inventive ability then it's actually cool.
However, generic shit, when taken to a high level, is almost always boring.

Manipulation: use a keyboard to give orders to a person by inputting bash shell commands. You have to be able to physically see the user and the complexity of the orders you want to give is directly linked to the time it takes to write a "script"
For important commands like "kill X" you'd have to have the person tell you a secret they haven't told anyone else which functions as a password.

How bad is that idea

Assuming you couldn't give an command such as:
>tell me a secret you haven't told anyone
then it's good and pretty balanced. Make it so only one person can be controlled at a time, though, and that the control wears off if the victim leaves the user's field of vision (or En?).
A good tactician could wreak havoc with that kind of power, yet it's not overwhelming or too destructive.

Yeah you couldn't give the order of giving you the password obviously.
Limiting it to what you can see is better than En, since that kind of ability would fit people who don't have great combat capabilities. It'd mostly be used for psyops.

Transmutation: The ability to create Nen with the properties of both rubber and gum

O

Enhancer. This nen grants invincibility if the conditions are met: it can only be used on criminals and can't be used to kill( if even one of this conditions is broken, the user loses his nen). This nen gets stronger during the night and if the user is wearing a costume

>invincibility
Too strong. Maybe Netero-tier speed and strength or something, that would be more than enough.

>that isn't broken

What's the fun on that?

>both rubber and gum
Two properties on one aura? Broken

Emmission/Manipulation: Mad Ruler
It manifests itself as a stand-like creature with a crown and googly eyes that can't physically interact with anything, like Hakoware.
The only thing it can do is enact a law, which is something forbidden to do for everybody on Mad Ruler's range. When a law is decided by the user, Mad Ruler says it out loud, but the sound of the command isn't physical, it can always be heard and understood by anyone in the range, and if someone else gets into range, the command is heard again, it's also periodically repeated. The command is in place and no one (including the user) can go against it, the user can change it but the change is noticed by everybody else, also there can only be one law enacted by Mad Ruler at any time.
The rule has to be something physically possible for everybody, for example the rule "It is forbidden to fall down in Mad Ruler's territory" is impossible, because it depends on gravity, but the rule "It is forbidden to breathe" is allowed. The rule "it is forbidden to use Nen in Mad Ruler's territory" is possible, but it instantly nullifies Mad Ruler itself, so it's pointless. There can be rules about specific uses of abilities, like "it is forbidden to stick you Aura anywhere" or "it is forbidden to create puppets".

MY

RUBBER

he is very cute!

Wormhole Dick: If you focus really hard you can make a wormhole to somewhere which only your dick can penetrate. It gets progressively more difficult to maintain without line of sight, with increasing distance, moving target, inside a body as opposed to open space or an orifice, and so on.

Superman(conjuration, manipulation, others to an extent)

The hatsu binds to the user's skateboard and through different tricks, different effects can be evoked. Every time a new trick is learned to a satisfactory degree by the user, a new effect can be bound to it. Effects can be anything simple from any category of nen, from making the board attack a target and return to the user to making the board more durable or able to ride on walls/ceiling for a short time.

If the board is broken, the hatsu goes inert until the user finds a board that looks and feels good enough and assembles the wheels and other parts while imbuing the board with nen.

The power of the effects depend on how well the tricks are performed, if the landing is sloppy the effect will be less or if the user fails and falls over the effect will backfire and be unusable with the current board. Chaining tricks and effects can produce effects with more complexity and power, but the backfire will be greater too if a trick in a chain is failed.

If the user lands a difficult series of tricks perfectly with a particularly liked board, they can go into superman-mode, where their physical and mental attributes along with their confidence and courage are boosted past their limits until the user steps off the board.

NEN

Early Birds: Emission

The user can create a max of 6 ghost birds that chase the enemy.

-The birds are incorporeal, they cannot be touched or hit by nen, they follow the enemy on their own without the user's control.
-Every bird has a 5 minutes lifespan before it disappears.
-The speed of the ghost birds is the same of a normal bird.
-There are 2 types of birds, blue birds and red birds.
-Blue birds make the opponent's aura disappear on contact for 3 seconds.
-If a Red bird make contact with the enemy, the speed of all birds gets doubled (including the ones created later against the same enemy).
-When a bird makes contact with the enemy it disappears and it has to be replaced
-The user cannot decide the type of birds to spawn but there is always at least a blue one and a red one (ex. max 5 red and 1 blue).
-To activate the ability against the enemy, the enemy has to be in a range of 1 km from the user and the user has to know what the enemy looks like, his name or they already made contact before (ex the hidden enemy attacked the user first with a nen attack)

It can be a lethal ability since without nen people are really weak, still difficult to handle. There are some cool things you can do with it, like know where a hidden enemy is if you already met him if he's in the 1 km range, letting the birds fly his way.