I have come up with a spell usable by some of my Alendyias characters: Crimson Clone. This spell was inspired by the Semblance of Blake Belladonna from RWBY and the Substitute move from Pokemon, and is further based off of my ideas off of how Substitute would work in an unfinished fanfiction project.
Basically, how it works is that the Adventurer with the spell takes half of their "vitality" or "HP"-leaving them sickly and weak, as when a Bloodmaker charges a gold metalmind explained here -and uses that with Aura, their own natural magic, to give the magic form and shape. This creates a duplicate.
Health is naturally regained after doing this, but it takes a few days. With a Healer paid to do so, one can return to full HP in a few hours and then make another duplicate, but duplicates aren't exactly that useful. Yes, they can stand in for their user and be an invaluable decoy, but they are also weak, generally ragdolling or dissolving into glowing red particles when struck by attacks. In other words, like monsters, they are solid but disintegrate when lethal damage hits them, and thanks to their generally paper-thin defenses, that's a lot of things.
They also have limited autotomy, meaning they have limited "programming" to act as a decoy. Once spawned, a decoy will either stay in place or follow the caster-whatever the caster intended upon casting Crimson Clone-with limited exceptions. Much like Warren from the second book of Fablehaven, back when he was almost catatonic, these clones have limited reaction capabilities, which are behind every exception to the stay put-follow caster rule.
How Clones React To The Environment:
1. Evasive Maneuvers: Clones will follow their caster into fire or freezing temperatures, but if placed somewhere without caster will rise and evade the adverse temperatures as best they can. Likewise, clones will follow their caster into danger, even if attacked, but otherwise get up or move away when hurt, and will avoid obvious dangers (monsters, sharp objects, projectiles) as best they can.
2. Easily Moved: If one takes the hand of a Clone just sitting or standing there, and then tries to pull them, they'll come along without resistance. Likewise, if a person grabs and sets down a clone, they will adjust to their new position and stay put. Clones if pushed will move forward or backward, depending on where the push went, and adjust to maintain balance-unless they are being pushed toward an obvious danger. Likewise, clones can be moved into a certain pose and will hold that pose.
3. Will Work with You: If one hands a clone a tool, they'll take it. Let's say you have a seated clone with a knife. Put a cutting board on their lap, place a long radish on the board, and then maneuver the clone's knife hand and arm to chop the radish, and they'll start chopping on their own until stopped.
Give a clone a spear, maneuver a thrust, and they'll keep thrusting. Have them thrust in a pattern and they'll keep it up until someone physically stops them and removes the spear, then resume thrusting when the spear is handed back. However, they don't seem to naturally claim tools and use them, and they can't adapt; even if the knife clone doesn't have veggies to chop, they'll keep chopping. The spear clone if attacked won't suddenly change tactics (block, thrust, or swing) even if logical because they lack true adaptability and only react, so they won't necessarily move away in such a way as to keep their spear thrusts aimed at you and may actually run away, back to you, while still thrusting the spear at whatever's in front of them.
TL;DR: clones avoid pain and sources of discomfort, as well as obvious dangers, unless following their caster. They can be led around or sat down and have a limited reactive capability, they can perform actions if physically made to do so, and will continue performing an action unless physically stopped and literally moved on to something else, or until the object they were using is gone, in which case they return to the position they were in, their default. If made to grab cookies from a plate and eat them, they'll keep eating cookies until the cookies are gone.
Summary: Clones, due to their natural tendency to note and evade obvious dangers, make great decoys (if someone shows up with a weapon, they'll run from them), which works great as that is generally their intended purpose. Due to their reactivity, they can be placed and posed, making them natural models, can hold things for someone, and can perform simple tasks after being puppeteered through the routine, so they can replace the caster for certain jobs they would rather not do with a little time unattended, though replacing a caster as they escape captivity doesn't seem too viable with a clone's unusually passive behavior.
With this in mind, are these clones useful for the caster, while also being relatively balanced? Relatively balanced meaning the clones don't grant some overwhelming advantage to the caster, like true clones could, and useful meaning they function well for situations where the user would generally use a clone.
I'm specifically looking for whether the spell is niche or versatile, overpowered or balanced.
Thank you for your feedback, I appreciate it!
Additional Clarification if Needed:
Making clones repeatedly within short timeframes wears out the caster, lengthening recovering time and increasing the chance of lasting sickliness. It's like donating blood or plasma, even if you try your best to recover, do it too frequently and you'll suffer nasty consequences. It can take up to two weeks to recover from creating a duplicate, or just 60 hours if one has 'upgraded' their spell recharge time to the max, but most mages haven't done that and don't need to, much like how most Pokemon trainers don't have or seem to want a powerful team.
Clones cannot cast like the caster (ergo they cannot create other clones), and as stated above, more or less just react to what's around them. Their limited intelligence, passive nature, and low defense makes them of little to no utility in combat (I think).
Casters do not regain the magic or essence used to create a duplicate when the duplicate is destroyed, just like for regular spells. Spells can be evolved, and one can modify the spell to regain something when a duplicate is destroyed, but in the end, they only get half of what they invested in the clone back, disincentivizing the creation of more clones using this feature.
The spell to create these clones is relatively new and/or rarely acquired, so such beings as these clones are currently unheard of. Word can, of course, spread relatively fast, potentially making this spell near useless to fool pursuers or captors. This is a significant risk for the characters that may access this spell, as like DnD players they are pulling some crazy stuff and dealing with notorious people and could very easily blow this kind of secret!
Clones do not need to eat or sleep, they are magical constructs with some life in them, sort of like Abominations in Owl House. However, they can and will eat if handed food and can be grown somewhat by doing so. Furthermore, I should add that a clone's durability can be increased, as it is directly proportional to the health of the caster and their Auric defense (as an extension of the body, Aura helps defend against harm, and its capability to do so determines how much the clone holds up under attack), both of which generally increase with time just as DnD adventurers become more hardy as they gain levels.