I had a few spidery ideas myself!
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Excerpts from the Codex Arachnos Avernus Vol. 1: The spider, that most-hated, primordial enemy of man. For all of recorded history, mankind has been in constant conflict with these, our most terrible natural enemy. Nowhere else is this battlefield so thick with the bloodprice of this war as the Hellworld of Avernus. While the most famous of Avernus' indigenous arachnids are the well-known and reviled Blink Spiders, a number of others have been found throughout the many terrifying and fascinating biomes unique to the world. A number of such creatures have been documented for reference, that future generations may never forget the knowledge so many of their predecessors gave their lives to secure.
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Stormsilk Araenid
Varieties of this energetic breed are native to regions commonly home to the Steelspark Spires (refer to Codex Arborium Avernus vol. 1), i.e: Lindon, Elysium and the Azure Islands. These creatures were first discovered near Storm's End when a particularly courageous, foolish and self-sacrificing member of our order decided to investigate the behavior of the local Steelsparks in the hours leading up to an inclement electrical storm. His discovery of the Stormsilk Araenid was made shortly before his death by fatal electrocution.
The chitinous exoskeleton of the Stormsilk is unique among all other spider species on Avernus. Rather than simple durasteel-grade chitin, the Stormsilk's hide is a remarkably effective electrical insulator. Mechanical tests have shown that the Stormsilk's flesh is all but entirely impenetrable to electrical energies and proves remarkably resistant to most plasma weaponry as well. The exceptions are small points located on each of the spider's limbs, its fangs, and its spinnerettes.
The spiders seem to live in a symbiotic relationship with the Steelspark Spires; extant specimens have only been found in close proximity to these trees or at very high elevations where lightning strikes are common. Typically, a single tree will play host to an entire colony of spiders, though they will often only reveal themselves immediately before and immediately after a thunderstorm-- or should the host tree come under attack.
As their name suggests, the Stormsilks are capable of absorbing and storing large quantities of electrical energy within their bodies. They typically seem to collect this energy by weaving vast, hyper-capacitive web networks. The spider will rest at the fringes of these webs in anticipation of incoming lightning strikes. The spider can then tap into the energy stored in the webs to fuel their biological needs. A large excess of energy seems to be stored at all times for use as a defensive measure: the spiders are capable of, individually, discharging energy equivalent to one-hundredth that of an average lightning bolt. Due to their numbers, and the fact that Araenids can amplify their electrical assaults by tapping into their battery-webs, this has proven to be a potent defensive measure not only for the spider colonies, but for their host trees as well.
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Vector Trap Behemoth
A bizarre and truly exotic variety of spider. Their existence-- or that of a creature similar to them-- has been long-since theorized by Avernite military personnel who have been faced with the question of where their vehicles (and vehicle crews) seem to occasionally disappear to. Only one specimen of Vector Trap Behemoth has ever been identified, lurking in the bowels of the Everglades. It was only through the cooperation of local Mycenid populations and the application of a powerful aphrodesiac and subsequent application of an even more powerful sedative that the creature was lured out and captured.
The Vector Trap Behemoth is a massive monster of an arachnid. The specimen retrieved from the Everglades was slightly larger than a baneblade. However, it's not their large size that renders them so dangerous. Like trapdoor spiders on other worlds, the Behemoth is an ambush predator. The difference being that the Behemoth does not lay in wait underground, but instead has the incredible ability to twist the fabric of the materium itself to create pockets of warped space. The Behemoth lurks within these space pockets and waits for prey to come near, whereupon it will spring forth either with one of its harpoon-like limbs or by lunging bodily from its hiding place. It will then paralyze its prey with powerful (though unremarkably so, for Avernus) venom and will either consume them outright, or simply store them within its lair.
The behemoth's weapons go beyond its impressive physical abilities and voluminous venom glands. The spider can manipulate the materium immediately surrounding it to defend itself as well. The Everglades specimen was capable of deflecting volumes of impaler rounds by using a pair of portals to redirect incoming fire upon its attackers. However, it does not seem to possess effective defenses against multi-vector attacks, and attacking from multiple directions simulatneously (read: at least eight) can overwhelm its capacity to redirect attacks.
Fortunately, the species seems highly solitary. Or at least, we have not detected multiple spiders hunting in close proximity. It may simply be that the behemoths are there, waiting, and simply haven't emerged from their lairs to feed yet.
The thought is as fascinating as it is terrifying.
Curiously, upon killing the Everglades specimen, the local materium suddenly disgorged a number of partially-digested corpses, and a wealth of material goods-- all of which have been quarantined for further examination. It is unknown, but theorized, that the Behemoths may also serve a role in preventing demonic incursions by preying upon the immaterium as well, but no evidence has yet been found.
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Annihilus Weavers
As with all things Avernite, the most frightening spider can be found deep in the bowels of the planet, within the so-called Caverns of Avernus. The Annihilus Weaver is a phenomenally dangerous specimen. It is not due to their size-- they are indeed only around the size of a grown man. It is not due to their venom, which is no worse than an average Blink Spider, or their speed. But rather, it is due to what they are capable of creating.
While most spiders can, in some fashion, spin a web, the Annihilus Weavers instead weave networks of pure and unrivalled destruction. Their threads are nearly invisible, warping any light that falls upon them in such a way that their presence is obfuscated to the naked eye. It's only by watching for distortions in the air where images are not quite where they aught to be that one can discern their presence. The reason, as I am told, is that reality itself bends around their webs. That is to say, the threads they spin seem to cut cleanly through the fabric of space and everything that occupies it. Should one for example brush a limb or a blade or a bolter against one, they will find the limb or weapon severed cleanly at the point of contact.
Thus, the Annihilus Weaver is so-named due to the fact that their webs annihilate all that they touch.
Were they passive creatures-- simply one environmental hazard among many found in the Caverns-- then they would not be nearly so perilous to encounter. However, the most terrifying property of these creatures is their tendency to weave vast orbs of obliterating webbing. These so-called Spheres of Annihilation are deployed as hunting tools, shoved down corridors like silent tumbleweeds onto unsuspecting prey. They do not seem to even be interested in feeding once they have killed-- we believe that they are somehow able to use their threads to directly digest their meals. That is, the moment you have touched their web, they have already consumed you.
Fortunately, killing a weaver will render its threads significantly less lethal (though still quite capable of killing you-- the web continues to 'digest' matter even after deactivation, albeit much more slowly) after some time has passed.
