Religions considered "Nethyric"
Nethyric Religions, in the views of Aethyric Druids, are Religions based on or around the worship of Nethyros, or "The Darkness."
These religions do not agree with the Druids, who are extremely vicious in pushing them to far corners of the world.
The Abdul-Qadir Arcanists
Worshiping the Darkness indirectly, the Abdul-Qadir are Zarosian aligned. The Arcanists, in their pursuit of knowledge on Zarosian magic, found a book to Typhoeus, or "The Darkness" and began reading it. Many of the leaders became mentally unstable as a result, passing this along to the membership. However, it is undeniable that they learned true power from the Darkness, though it made them more prone to opening portals that the smaller Nethyric Demons could bleed through.
The Abdul-Qadir worship magic overall, and believe in the return of Zaros, though they are not sure when it will come. The Arcanists have tampered with much darker magic than Ancients to try and bring Zaros back as a large Demon would be, or a powerful undead. So far, it has failed. But there is no doubt that if the Empty Lord calls them to fight, they will fight with unmatched fury.
One of the three faiths that actually worship Typhoeus in some form, this is one started by Diokiti Lex in Wushanko. Initially seen as a gathering place for crazies, the religion was later proven to make people crazy.
Chin-Chin, or Chthonian Occultists, worship Typhoeus as the God of the Dark emerging to Gielinor. With Typhoeus' death, Diokiti Lapas has hijacked the religion to serve his own needs, just as his parent would have wanted. Much of it is centered on power and sacrifice, but said power causes crippling insanity in those who earn it by blood.
The Fearghal Secession
The Fearghal embrace the Darkness, but do not worship it. They are also the only ones to call themselves "Nethyric Druids." Led by Leone Fearghal, a wicked nature spirit, the Fearghal have enhanced Druid summoning so far as to bind themselves to animals. Aside from the Four Fearghal children and their mounts, there are also snake, wolf, and spider druids who are one with a familiar, and can control it much more deeply.
A hybrid of Zamorakianism and Aethyric Druidism, the Fearghal believe that the weak will die and the strong will survive, pushing themselves closer to their goal. They are Guthixian, but it is very easy to say they are two steps away from being Chaos Druids.
The Hero Cult of Zarin Renderra
The Hero Cult of Zarin worships all they can find to tie to Zarin. They are convinced Zarin is the newest embodiment of "the Darkness," as a God. They have made altars and statues to Zarin, only aiding to boost his ego further into fighting stronger creatures, though the Cult never made direct contact to their hero.
The Hero Cult believes Zarin is the idea of "The Darkness" working to do Good in the world, rather than the evil other groups aligned with the Dark have done. They worship him as a "Darkblood," and a strong one for positive change at that. They seem to worship the Renderra overall, at least those with Mahjarrat genetics, and have even slipped under the radar of Aethyric Druids as a potential threat.
The Marcato Coven
The Marcato Worship "The Darkness" in the form of Lerepiel, believing the Infernal to be Nethyros, the being responsible for the poisoning of Aethyros and the death of the Arrenda Unity. They do this in order to gain power from Lerepiel to crush their Renderra foes, though Lerepiel never was Nethyros as much as another victim of the being.
The Marcato worship Lerepiel, and as a result are Zamorakian aligned. They have a religious fixation on Undead, and the heads of the Coven are always a Lich of Marcato descent, until Lerepiel's son could rule, that is.
The Marcato today, aware they were wrong, battered, and broken, have been turned away from Lerepiel and instead continue to practice Necromancy in the Deep Wilderness.
Following Oavatos, a Lich born of Lucius' memories of Typhoeus, Oavatos is the epitome of beings immune to Typhoeus' madness abilities. His following are mostly undead and liches, who follow his every order. They are currently disbanded, due to Oavatos' death.
While Oavatos was alive, the Religion followed his every whim as a being of pure darkness. In fact, the Renderra believed for a while Oavatos was the truest form of Nethyros possible. Oavatos is Zarosian, or was. It is easier to say Oavatos began to worship himself as well as time moved on. His castle is still considered to be haunted beyond any form of sanctity, made to resemble Camelot in parody of Lucius Renderra.
Many groups have sworn to fight against Nethyric Religions, for many reasons.
Believing in Magic, and patience, the Traditionalists staunchly oppose the Arcanist faction of their family, and seek to root out the disease on their family tree. Overall, not great people. They practice incest heavily, and are overall just as horrid a cult as the Arcanists. However, they keep to themselves enough to make good allies in a pinch.
Of course, this is the anti-thesis to the Nethyric Religions. Both have struggled bitterly for long periods of time. Suffer from many of the flaws faced by standard Druids, but are also the most equipped with the knowledge to hold Typhoeus from the mind.
The Enlightened Order of the Crown Archival
Sworn to embrace Saradomin as a God of Light, the Enlightened Order views anything worshiping Darkness, or anything other than Saradomin for that matter, as sacrilegious. They are a good example of how groups against Nethyric Religion, do not necessarily agree due to their bitter hatred of the Order of the Raven.
The Flames of Armadyl
Embracing Armadyl's Phoenix persona, the Flames of Armadyl are devout in the name of Justice. They have met Nethyric Religion before, and had horrible experiences. They have asked for Armadyl's graces to fight the Cults and their grip on Gielinor, and were granted it by higher commanders.
The Order of the Raven
Founded by the Renderra to protect the people of Gielinor, the idea of a Chthonian coming is catastrophic. Ravens of high and low ranks, from allies such as Caelan Soulwood to Zarin Renderra have fought Nethyric Religion head first.