Ahem,
Let's try this again.
As always, welcome, and thanks for making a suggestion.
As I said initially, best thing to do when you're interested in suggesting a new effect is to look closely at the existing Signature Attack Effect list and work out how the effect you want can most closely be simulated in the current rules. Once you do that, you'll have a rough gauge for where the power to cost ratio lies, at least more or less. If the thing you want to propose would be, by those numbers, a lot more powerful than any similar available alternatives, or if it comes out to be ineffective compared to achieving the effect a different way, then you'll probably need to reconsider it in some ways or rescale it to suite the rest of the system's balance.
You've given us a concept here, and it's a fun idea, however the way you describe it mostly sounds like it's a very personally specific function and concept that you've got in your mind, for a very specific navi. That being the case, it may work well as a theme for your character, but such things usually aren't a good candidate for being turned into standard effects that we can add to the Signature Attack Effect list. Let's have a look at it anyway, though.
Most of what you suggested sounds like it would be neat for the particular character, and would be cool as long as the character is doing role play, social interaction and other non-combat activities. The moment it drops into a combat situation, however, the actual effects and functions of the ability have to fall in line with the system rules and limits.
So what can we do? What do we have to work with?
The effect is intended to be ale to create several independently acting entities out of one single navi, that are each capable of doing things at a reduce rate, while also having tangible hp, and are in terms of stamina, a real part of the user. This is difficult in the current system, because of the way combat works, but there are a few ways we can try to mimic it.
The first is with decoys; they're effectively shadow clones of your navi, but they are limited in a few ways that may make them unsuitable as an option ,at least if used on their own. For starters, they don't have Hp pools, and on their own the can't make attacks. They also aren't proper entities, in that they don't have formal actions of their own, though you are generally allowed to describe their movement and behaviour freely, within reasonable limits, as long as they're active. They are tangible, in that they can touch and interact, and if you want them to, speak, etc., but not in the same way that you seem to be after.
Duration is important too. In combat terms, whatever you do, there can be no 'lasts for 24 hours' thing possible. No combat effects remain between combats, at all, and that's not likely to change. You also wouldn't be realistically allowed to have the duplicates be far enough remote from you to the extent that they could engage in different combats, or different major events — it would be a pretty direct cheat on our rules dealing with navi continuity etc., so don't expect that to happen either.
All the details about retaining memory, or experience, is all aesthetic; it's up to you, and we wouldn't be likely to rule on it one way or the other, in the name of player creative freedom.
Another way we could try to mirror this effect would be with object summoning. A signature that summoned an object, with an attack of some description built into it its entirely doable in this system, and if you're a summon type navi, you can do a fair amount with your object summons.
You could make an object that summons as a physical replica of your self with a hit point pool, and with a directable movement, an attack of some kind, or even attacks and movements each turn, if you were willing to pay the passive signature cost for that. It would be very expensive to do this to any useful strength, but it would work. Essentially, to make an object of yourself that could move once and attack with your buster once each turn, would cost you 150 sig points, plus the amount of Hp you wanted to give it. You could balance that with Hp sacrifice nerfs from the user, for thematic purposes — either lowering the eventual cooldown of the signature, of having to spend fewer points from your actual pool to achieve the effect. Something like that might be acceptable, though I'm a bit hazy on how 'animated' such an 'object' would reasonably be allowed to be — if objects can be as animated as Decoys, in terms of how they look and behave, then that mostly renders decoys pointless, so, there would need to be a limit. If you wanted to take this path, though, we could work around it, again, at cost.
An in between option might be to create decoy signatures, and utilise the Hp sacrifice nerf to get the most potential out of them, as well as making yourself some passive attacks not specifically attached to anything; you could then describe the passive attacks as taking to form of being utilised by the decoys. Visually and aesthetically, it would be clones attacking, even though the underlying mechanics would just be using our existing systems.
Those are the sorts of things we can do currently to mimic this effect. So, then we ask, what can we propose as an effect that is acceptable in the power to cost balance of the system?
I might suggest something like this:
Duplicate: 80 (Per Duplicate, Per turn) Creates a duplicate of the user that shares their HP pool and actions. The user's HP is divided evenly amongst the number of duplicates created, including the original, and the maximum Hp of each duplicate so created is equal to the user's max Hp divided by the number of duplicates created by the signature plus the user (Max Duplicate Hp = User Max Hp/(Duplicate Count + 1)). This means that Duplicates will not be created with their potential Max Hp, if the user is not at full Hp when they create them. Creating Duplicates does not duplicate defences, wielded gear, status effects, buffs or debuffs; a physical body with Hp is all that is created by this effect.
The user retains the same number of actions while duplicates exist, and must share them between all duplicates. This means that if the user has 5 actions normally, and they use one action to use a signature that creates duplicates, they then have an additional four to use, and must allocate them specifically; for example, this might mean using one action with the original to dodge, one action with a duplicate to use another of their signature abilities, and two more actions for a second duplicate to cross the room and activate a console. If a duplicate is destroyed before carrying out its assigned actions, those actions are simply lost.
After creation, all are capable of attacking and receiving damage, however the original retains priority; automatically activated NC programs, such as Undershirt, trigger only on the original, for example. Activated NC programs, such as Shield, can still be manually used by Duplicates. The duplicates do not share damage but sustain it individually and a Duplicate is destroyed if their personal pool of Hp is depleted.
When the duration for a duplicate expires, if it is still alive, it disappears and all of its remaining Hp, Defences, Equipment, Effects, Buffs and Debuffs (including status ailments), are returned or inherited by the original navi. In the case of conflicts (multiple duplicates expiring at the same time, or a duplicate expiring while possessing conflicting defences or gear to the original), the navi must still follow the normal rules and may retain only one effect for each defence layer that limits them, as well as no more than two wielded equips. Each conflict is considered independent, and multiple Hp defences do not stack or add on; the navi simply chooses which one to retain.
For Example: DupeNavi has three Duplicates, which all expire at the same time. DupeNavi has a 30Hp casing, while one of her duplicates has a 10Hp Casing and a 20hp barrier, and a second duplicate has a 2-Hit Shield and a Sword chip, while a third duplicate has a Varitails and a Pillow. When they expire, DupeNavi would need to pick between the two casings — 30Hp or 10Hp, and could not claim to have a 40hp one. Despite forfeiting the 10Hp casing from the first duplicate, she would still inherit the 20Hp barrier from it. She would also need to to make a choice between the three weapons and the shield, forfeiting at least two, so as to only retain two wield slots.
If the original navi is reduced to zero Hp while Duplicates remain the effect immediately ends, as though the remaining Duplicates had expired; the left over damage is subtracted from the new aggregate Hp, potentially preventing an EJO if the new figure remains positive.
This proposal essentially uses the 'divided' effect that some viruses have. This gives the user versatility and a certain amount of unpredictability, but it also come with some steep risks. The navi can effectively be in multiple places at once, but they also become multiple targets, all capable of sustaining damage from AoEs and other multi-target risks. Similarly, they would be able to potentially benefit from positive multi-target effects, such as a heal that can target three allies.
This would be my mechanical suggestion for making the desired effect site-viable. I would still recommend taking a good read over the Signature Attack Effect list, though, and the battle rules, to get a firm understanding of how the combat system works, and what principles combat effects will need to abide by. Do swing by the chat some time and say hello, so I can apologise for my first post ^.^
-Rogan