Mechanics/Cultist Origin

Divine Sorcery
You've been indoctrinated as an Architect of Arxsec. You've chosen an approved domain and are ready to spend your years creating and maintaining dungeons based on it, as well as doing the office work necessary to operate Arxsec's Rift among the other cultists. A ritual has been performed, imbuing you with Arxsec's divine magic - a root of sorcery, with a few ties from other casting classes sewn in. Perhaps you were already one of those casters, or a non-casting class, or perhaps you were deemed worthy of training all the way from level one.

You'll get many benefits of self-expression, including arcane physical features, magical abilities unique to your domain, and a multitude of areas to mold and call your own (one of which is the office you're required to have). That is, so long as you fill the requirements set by Arxsec: hone your dungeons, pour your domain and self-expression into them, shepherd the many people calling the Rift home, send them through your dungeons both to tame the powerful energies that manifest in them by nature and to spread the influence and ideals of both Arxsec and your domain, and most of all, protect the Rift.

Physical Traits
As an Architect of Arxsec, you'll gain many extra spells, spell slots, and sorcery points - mostly for utility and healing. You gain divinely imbued darkvision. You gain immunity to conditions and resistance to damage types related to your domain, as determined by your DM. You have immunity to those damage types when they come from manifestations of your domain areas.

You also gain flavor traits and abilities related to your domain, as determined cooperatively by you and the DM. Examples of this include a trail of frost, harmless dripping acid (that sizzles and evaporates, but doesn't to physical harm or induce pain), extended versions of Druidcraft (also creating small bursts of flame, freezing over surfaces, creating non-harmless acid, etc), and minor illusion as a cantrip (rather than a spell).

If taking Sorcery as a multi-classing option, you gain proficiency in concentration checks but not in general constitution saving throws.

Extra Known Spells
In addition to your known spells as a sorcerer, you know the following spells (provided you have slots for them) - but if you get to choose a damage type from a spell, it must be related to your domain: Additionally, you know any spells related to your domain, as determined by the DM.
 * Cantrips:
 * Light, Mending, Mold Earth
 * Dimensional Navigation
 * [spell details TBD]
 * 1st: Chromatic Orb, Cure Wounds (plus 3d8 if the damage was related to your domain), Comprehend Languages
 * 2nd:
 * Continual Flame, Lesser Restoration, Misty Step, Prayer of Healing (plus 2d4 if the damage was related to your domain), See Invisibility
 * Spiritual Weapon (but the weapon acts as as an item and cannot levitate or act on its own, the bonus-action attack is removed, and if it is made into a ranged weapon it makes a ranged attack instead of a melee attack)
 * 3rd:
 * Catnap (but once per week, instead of changing a short rest, you may choose to shorten a long rest to one hour and the target is up to eight creatures which are willing or make a wisdom saving throw)
 * Dispel Magic, Protection From Energy, Remove Curse, Revivify, Tongues (but has a range of Self)
 * 4th: Stone Shape, Dimension Door
 * 5th (caster lvl 9+):
 * Creation (but while using it to morph your domain areas, the dimensions are unlimited, all non-food materials are permanent, you may destroy matter in a similar fashion, and you may freely use the spell in this way for a duration of 30 minutes)
 * Greater Restoration, Scrying (+5 to spell DC if looking into your domain areas), Raise Dead, Transmute Rock
 * 6th (lvl 11+): Globe of Invulnerability, Heal (plus 40 points if the damage was related to you domain), Move Earth, True Seeing (but has a range of Self)
 * 7th (lvl 13+): Resurrection, Teleport (but has a range of Self)
 * 8th (lvl 15+): Dominate Monster
 * 9th (lvl 17+): Mass Heal (plus 300 points if the damage was related to your domain), True Resurrection, Time Stop, Wish

If you take one of these spells instead as part of your normal Known (or Prepared, if multi-classing) Spell Limit, you may choose to either cast the spell exactly as the core rules describe it (as a "normal spell", under the rules below) or as it is described in the above list (as an "extra spell").

Extra Spell Slots & Sorcery Points:
You gain additional spell slots equal to those you know as a normal spellcaster, but they must be used only by the extra spells you know as an Architect of Arxsec (though you can cast those spells using your normal slots if you wish). For this reason, it is recommended you keep a separate spell sheet specifically for those spells and slots.

The same goes for sorcery points; you have a separate pool of points equal to those you know as a normal sorcerer, but they must only be used for these extra spells and these extra slots can only be burned for or created from your extra sorcery points, though you may use your points as a normal sorcerer on these extra spells and slots if you wish.

Slots & Points rules TL;DR
("energy" refers to slots and points): For example: as a 10th level pure sorcerer, you have three normal and three extra 3rd-level slots; you may cast Remove Curse six times, but you may not cast Fireball six times.
 * When you cast an extra spell, you may use either type of energy.
 * When you cast a normal spell, you may use only normal energy.

6th level:
[TBD]

14th level:
[TBD]

18th level:
[TBD]