u/Beautiful-Guava-7692

I had an idea for a Special Grade cursed technique called Blood Archive and I wanted to know what you guys think about it.
The technique summons an old book that works like an archive of forgotten sorcerers. Every open double page contains one cursed technique. On the pages there is a drawing of the original user, a short biography, an explanation of how the technique works and also its strengths and weaknesses.
The user can only use the technique from the page that is currently open. If the book closes, the cursed technique instantly stops working and only one technique can be active at a time.
The book has around 40 cursed techniques so about 90 pages in total. The techniques are fixed forever and cant be changed or added. Every original user has been dead for atleast 100 years. Every technique has to be an innate cursed technique, inherited techniques are excluded and there are no Special Grade techniques in the book. Most of them are around Semi Grade 1 or below, with only about 13 Grade 1 techniques.
The idea is that the user isnt overpowering people with one broken ability. Instead he wins by picking the right technique for the situation, almost like Batman with prep time. I wanted it to feel more like an archive of forgotten cursed techniques than just another copy ability.
For example one Semi Grade 1 technique lets the user turn everything he touches into a bomb. That makes it really effective against groups since multiple targets or objects can be turned into explosives very quickly.
Another technique is around Grade 2 and lets the user summon two durable shikigami. They arent extremely powerful on their own but they constantly pressure the opponent, create openings and make it easier for the user to fight strategically.
Do you think something like this would fit into JJK or does it still sound too overpowered? Im trying to make the strength come from versatility and planning rather than every individual cursed technique being insanely strong.

Nen Ability: the Creater
I’ve been working on a Conjuration ability and wanted to make something that feels versatile without becoming overpowered. Instead of conjuring anything I can imagine, I’m permanently limited to only four objects. Each one has a unique role, duration, and aura cost.
1. Trampoline
Aura Cost: 1
Duration: 3 seconds
The trampoline is my main mobility tool. I can place it beneath my feet to launch myself at insane speeds, use it to instantly change direction, or even summon it behind my elbow, knee, or fist to massively accelerate a strike. It’s cheap, fast, and incredibly flexible.
2. Katana
Aura Cost: 3
Duration: 1 minute
This isn’t just a normal sword.
It allows the katana to become transparent for a brief moment, making it much easier to reposition or catch an opponent off guard.
It also has a secondary effect: if I land three successful cuts on the same target, they lose roughly 60% of their muscle control. Their movements become sluggish and uncoordinated, making it much harder for them to fight effectively.
3. Truck
Aura Cost: 10
Duration: 10 seconds
I conjure a full-sized truck that charges straight toward my target.
If necessary, I can detonate it for massive damage.
Summoning the truck costs 10 Aura Points.
Triggering the explosion costs an additional 10 Aura Points.
It’s my highest-risk, highest-reward option and isn’t something I can spam.
4. Rope
Aura Cost: 3
Duration: 5 minutes
The rope is mainly for capture and utility.
It can bind opponents and restrict their movement.
Its special ability is that anyone touching the rope is incapable of lying. As long as they’re in contact with it, every answer they give must be truthful.

General Rules
This is a Conjuration ability.
I cannot create any other objects besides these four.
Every summon consumes Aura Points.

The idea is to have an answer for different situations:
Trampoline for speed and movement.
Katana for dueling and disabling opponents.
Truck as a devastating finisher.
Rope for support, interrogation, and crowd control.
I wanted something that rewards creativity in combat rather than raw power. The trampoline in particular can be used in countless ways depending on the situation .

How would you turn Gremmy’s ability from bleach (The Visionary, where he can turn imagination into reality) into a Special Grade cursed technique in JJK without making it a “calamity level” power?

It should still be strong and Special Grade, but not on Gojo or Sukuna level where it feels basically unstoppable . What kind of limits or rules would you add so it stays balanced?( i feel like limiting it too much will make This ability much worse) .