Creating Powerful Mutated Servants from Existing Mobs in Goety Cataclysm
Creating powerful mutated servants from existing mobs is the core of Goety Cataclysm's necromantic progression. Each of these servants begins as an ordinary creature that is transformed through ritual, possession, or resurrection into something far more dangerous, and each one has its own upkeep, healing rules, and way of cheating death.
Ancient Remnant
The Ancient Remnant is what you get when you invest serious materials and magic into upgrading a Modern Remnant. The result stands on equal footing with the being it descends from.
Feeding it bones restores its health. If its owner wears a Necro Cape, it also recovers health on its own. Once it reaches its second phase, that passive regeneration keeps working even while it is burning, and it no longer waits a second between healing ticks.
Draugr Necromancer
A Draugr Necromancer is created by performing a ritual on a Draugr rather than on a Skeleton. It fires arrows made of phantasmal energy and calls up Draugrs to fight for it.
You can expand what it summons. Right-click it with the appropriate focus to teach it to raise Elite Draugrs or Royal Draugrs. It cannot summon any other kind of undead servant. Right-clicking it with an empty hand makes it summon Undead Servants on your behalf. It heals the same way ordinary Draugr Servants do.
If a Draugr Necromancer dies while you carry an Empty Soul Jar, its soul is captured inside. Right-click that jar on a Draugr to bring the Necromancer back, using that Draugr as its new body.
Ignited Berserker
The Ignited Berserker comes from letting a long-dead warrior's essence take over a fire elemental. Despite the obvious risk, the outcome is stable.
Bones, 
Blaze Rods, or 
Blaze Powder all heal it. A Necro Cape on its owner grants it passive regeneration. When one is extinguished, it leaves behind a burning core; that core can take over a Blaze and bring the Berserker back.
Ignited Revenant
The Ignited Revenant is a product of combining blaze knowledge with necromancy, letting you raise your own burning undead.
It accepts bones, Blaze Rods, or Blaze Powder as healing. A Necro Cape on its owner gives it passive regeneration. If its shields break, hand it a 
Netherite Scrap to restore them. When extinguished, it drops a helm, and that helm can possess a Wildfire to return it to undeath.
Kobolediator
Starting from a plain Koboleton, you can bring back a Kobolediator and bind the mighty undead gladiator to your service.
Bones heal it, and a Necro Cape worn by its owner lets it regenerate passively. When it falls, it leaves its spirit behind. That spirit can possess a Koboleton to bring the Kobolediator back.
Wadjet
The Wadjet is also called forth from a plain Koboleton, giving you a great undead spellcaster under your control.
Like the Kobolediator, it is healed by feeding it bones, and it regenerates passively while its owner wears a Necro Cape. On death it drops its spirit, which can possess a Koboleton to revive it.
Choosing and Maintaining Your Servants
Every servant here shares two things: bones as a reliable healing item, and the Necro Cape as the way to unlock passive regeneration for the whole group. Beyond that, each has its own extra fuel or repair item, and each has a distinct revival path tied to a specific host creature. The Draugr Necromancer is the exception among them, since its revival depends on an Empty Soul Jar and a Draugr body rather than a dropped token.
Covers the mod’s in-game guide topics: Ancient Remnant Draugr Necromancer Ignited Berserker Ignited Revenant Kobolediator Wadjet
Soul Jar