Enemy types in Aelsif

The primary purpose of this thread is make sure that each category is sufficiently distinct. The goal is that they'll all feel fundamentally different to fight, and it should be in ways that are intuitive given the kind of creature they are. I am looking for feedback towards that end.

Aelsif has a great deal of enemy variety, with different tactics generally being needed for different enemy types, in a way that makes each actually feel different to fight. These can generally be sorted, though, into the following categories: Animals, undead, grand illusions, automatons, NPCs, immortals, spirits and aelforms, as well as hybrids of the previous categories. These are more or less in the order of least challenging to most challenging, but of course a strong creature from a weak category can be stronger than a weak creature from a strong category.

Animals:
Animals are, arguably, the least threatening category of enemies in Aelsif. Primarily encountered in the first 5 levels or as the first encounter in a new region, animals serve to teach new players the mechanics of the game. Animals usually don't do a lot of damage, nor do they usually have good defences, but they always have at least one thing they're really good at and they base their entire fighting style around setting up that ability. This thing is what they're intended to teach the player to deal with, because finding a way around their strongest trait makes them pretty trivial. That something may be a special attack, a skill, a defence, or anything else. Some are still intended as boss fights for tutorial-level (1-5) players, and these tend to have a couple things they're good at, but only a few, and one is still their main tactic.

Undead:
Undead are (usually, but not always) animals or NPCs, but they're a bit different from normal in that they're defeated only through the wounding mechanic. They are easily dropped to 0HP, which knocks them down and resets their health to full. However, each drop to 0HP will inflict a wound on the undead, lowering their max HP and impairing their functionality in a way dependent on the wound. It may just lower HP, it may lower defences, break a leg, hack an arm off. So each time they're knocked out they get weaker, basically. Eventually, you'll lower their max HP to 0 through repeated wounding and they'll be stopped completely. Alternately, the wounds can render them sufficiently incapacitated you're free to just walk away and get full XP since that's still a win. Either way works, and choosing damage types whose wound tables are conducive to what you're trying to accomplish isn't a bad idea. Slash damage, for example, is very good at disabling limbs.

Grand illusions:
I may need to make an entire thread on this one, because it's a complicated concept. Grand illusions are illusions that are also, in a particular sense, from a certain point of view, if you stretch a few definitions, "real". Or at least, they're "real enough". Real-ish. Reality lite. In this instance, we're looking at grand illusions of creatures. They're how conjuration is handled in-game, a creature is not called from somewhere else, they're generated on the spot. And while they are, and I do mean absolutely are, an illusion, they're an illusion able to operate independently, communicate and learn, they even seem to have wants and needs, and a personality, which raises a LOT of very uncomfortable questions. Grand illusions need to make an attempt vs Will to pass as real, with those it failed to convince being far more capable against it. All their attacks target your will defence and they do not roll to randomise success and failure, so at any given time they either will hit or they won't, though this does depend on the exact attack and circumstance. Lastly, they have 0HP, a single point of successful damage will end them on the spot, but their defences tend to be very high and they sometimes even have DR, so a hit that's too weak won't count.

Automatons:
Automatons follow strict instructions. They have a fixed attack pattern they continuously used, generally with a short list of options their operator chooses between and they only perform one action per round. This is offset by them being extremely powerful, with mediocre accuracy and defence but far too much damage to be taking hits from and a lot of DR that you may need to actively try to overcome, IE, by using a damage type they're less resistant to, by power attacking or by scoring critical hits (which, due to the critical threshold system, can require some set-up). These fixed patterns, in combination, can form pretty good encounters. These are used to make puzzle fights, but puzzle fights are hard to do well so I strongly urge you not to use automatons if you're not confidant in their use. They can easily TPK if used improperly or with a party that fails to realise the fight is actually a puzzle and try to brute force it instead of figuring it out.

NPCs:
People are a dramatic step up in difficulty, in their own way. Even very low-level NPCs can be dangerous to high-level parties, and this is due to them being intelligent, using tools and the advantages that come from a well-planned encounter. NPCs can lay traps, engineer weaknesses in their opponents and exploit an enemy's weaknesses ruthlessly given the information and tools to do so, a lot of which they can figure out or improvise. When fighting NPCs the combat is highly tactical and mostly based on playing your strengths against the opponent's weaknesses while also shielding your own weaknesses from an opponent's strengths. As a result, NPCs should never be used against new players who haven't figured out the combat yet.

Immortals:
Immortals are an extra modification to a pre-existing enemy type. Basically, take an enemy you previously could trounce and add on a few special traits. They regenerate, never die except for through the wounding mechanic reducing their max HP to 0 and are only able to be critically hit by certain attacks, such as thrusts and projectiles, that can hit their heart. This means the best way to down them is to use attacks that can crit, do the best you can to maximise accuracy in order to score those crits, and make sure once they're down to finish them off because if you don't they'll live to fight another day, or even reach positive HP again during the same encounter and either catch you off guard or escape while you're not looking.

Spirits:
Spirits could be considered a development on the concept of immortals. I already made an entire thread on the details, but I'm not assuming you've read it, so I'll summarise, but it's a complex concept so this is going to take longer than the other sections. Spirits are tiny fibrous creatures, which primarily generate and use supplemental structures and grand illusions to take a form that helps them belong in the world they're in, further cemented by them not actually realising it's an illusion. The fibrous creature, or "sprite", can create both the aforementioned physical framework, called their "body" and a more flexible short-term "ghost". They can also create very simplistic projections if they lack the energy even for a ghost body, but that's a story for another time. There are advantages to the more physical "body", namely durability and power since it's actually a physical framework the sprite docks into, but the ghost body regenerates faster and is able to shape-shift, since it has no such framework and is just a shape the sprite's fibres are presently arranged in. Unfortunately for them, though, while taking a form other creatures are comfortable with does definitely help them find a role in the world, spirits are easy to tell apart from real creatures because the grand illusion is just not very detailed and tends to be a bit "off model", especially their ghost. For example, compared to a real humanoid, a humanoid spirit's head tends to be larger and their eyes especially, but their feet tend to be smaller. And as a ghost, they have no solid structure or joints, so their limbs are loose noodly appendages, they don't have fingers or toes, their head is almost as big as their body, their eyes and mouth are gigantic and they don't have hair or a nose, their head is just shaped like hair and a nose.

As for how this arrangement works out in combat, spirits tend to be weaker than real creatures, but they regenerate and they can eject from their body at will. If their body is too damaged to function (so, if you deplete their HP), they'll cannibalise their body, disintegrating it to ash, healing and protecting their sprite with a barrier while it ejects at supersonic speed. If their sprite takes too much damage, they'll also have to cannibalise their body to save it, and that still means they're ejecting. In their body, they can only be killed permanently if they're completely obliterated. As a ghost, they lack the resources to resurrect a destroyed sprite and if you kill their sprite they'll die for real, and if the ghost is destroyed without destroying the sprite itself they'll eject but not nearly as fast and minus the self-repair and barrier disintegrating their body provided. If they're defeated in their body, they will still have the energy to form a ghost straight away once they land, but a new body will still take quite some time to generate, and if they're in ghost form and are defeated they won't have the energy to make a ghost for a while but they're still alive. This means you're fighting an enemy with two distinct phases, which has an excellent opportunity to escape at the end of each of them (usually). They're not hard to defeat temporarily, but it is very difficult (though not impossible) to kill them permanently. This means spirits you've defeated previously tend to come back later with a vengeance.

Aelforms:
Aelforms are another expansion upon immortals, and the one more central to the way the setting works, and to why immortals and spirits are the way they are. Aelforms are distributed organisms with few speciality organs, of which only their core is essential to life functions and the rest regenerates. Many other systems for which other creatures have dedicated organs are distributed throughout the aelform's body, such as their nervous system and their open respiratory system (and they can function anaerobically anyway), meaning they cannot be damaged too severely to survive so long as their core is intact and has resources to regenerate their destroyed body parts with. Their cores are buried deep inside their armoured chests, and while other aelforms all have long, stabbing weapons meant to hit cores not everything else does, and even then they're well built to protect their core and the core can survive much more damage than an immortal's heart or a spirit's sprite. This makes them functionally invulnerable to animal life on Aelsif, since even being beaten to a bloody pulp and having limbs ripped off is only a temporary inconvenience and few animals have a stabbing weapon able to penetrate their body through chitin armour and reach that core. Their main weakness is people, as intelligent races have things like "spears", and "swords", and "bullets" that are quite able to hit their core. Even then they can be hard to take down since they have a lot of critical resistance while functional and more or less need to be downed in combat before those fatal core-shots will be possible, and it may take a few. Worse yet, even very simple aelforms have the ability to actively heal themselves on top of their passive regeneration and their regeneration is 10x faster when downed, so if you stop hitting one briefly it'll get right back up in a round or two. All this combines to make them an absolutely unrelenting foe that just will not DIE. Oh, and they sing. They're a strong candidate for "hardest enemy type in the game", and the only reason there's any question at all is because of hybrid enemies.

Hybrids:
Very, very often creatures will fit into more than one of these categories. Such enemies will have the features of both. Some categories are always or nearly always a hybrid, for example undead are nearly always a variant on animals or NPCs. (Though pure undead, abominations made out of a collection of animated corpse parts, do exist.) For example, Aeldyans are intelligent aelforms that are both Aelforms and NPCs, except instead of class levels they have their own unique progression based on the specific type of Aeldyan in question. As such have the benefits of tactical thinking, coordination, traps and tool use. This means they're far more dangerous than regular aelforms, especially if they're prepared, and are dangerous even to players much higher level than their rating suggests.