If you want access to the spells, you have four options:
1 - Conjuration vendors who will release them once you hit the appropriate conjuration levels as in vanilla
2 - If you want to start your game with some spells, use the Dead & Daedric Guardian Options lesser power and select Quick Start. 
3-  Head to the Necromancer's market. It resides on a little island south of the Blue Palace, just past the ruins of Folgunthur. 
More about the market:  

4 - Direct your character to a few lore-friendly locations where you may encounter them organically
More info:  

 
The Undead Guardians 
 
 

The Daedric Guardians 


Homunculi Guardians 

 
 
Soul Anchoring (optional)  
 
By default, all guardians require one filled soul gem to create.

The Soul Gem, but not the soul, is the only ingredient to survive the destruction of a guardian and can be looted from the dust pile that remains.  
 
Role play wise, this is what anchors the soul or daedra in place, so that these minions are not dependent on your presence or limited in number like other summons and reanimated minions you can create in game.  

Game play wise, this requirement is the main balance mechanism which places limits on one's army and provides a sense of effort and progression to the process of creating it. It can be disabled through the options menu (see below).

 
Bone Harvesting 
 
All skeletal guardians (with the exception of the dragon) require a fully intact skeleton and one filled black soul gem (unless disabled in options).  A skeleton is made up of 10 pieces which can be harvested from corpses, be they fresh, draugr or skeleton. Not all bones are in good enough condition after you have bludgeoned or blasted their former owner to death, so you may have to harvest a few corpses to get a complete intact set. To harvest a corpse, you will need the following item or spell, which can also be purchased from conjuration vendors and may also turn up elsewhere.  
 
1) Tool (1h Weapon) - Crude Corpse Harvester 
Use on a corpse (be it fresh, draugror skeleton)  to extract intact bones from the remains. 
 
2) Spell - Harvest Corpse (Adept) 
A spell for harvesting the bones of corpses (be they fresh, draugr or skeleton) as an alternative to getting your hands dirty with a Crude Corpse Harvester. 
 
Mummifying 
 
All corpse guardians require a fresh corpse and the resources to mummify it. This includes salt and embalming fluid. Embalming fluid is a new potion available in level lists and so from appropriate vendors. It can also be crafted at a cooking station. Requires one filled black soul gem (unless disabled in mod options).
 
Ritual Offerings 

Atronach guardians can be coxed from oblivion with the correct ritual offerings. These include fire/frost/void salt and pelts from dangerous beasts. In addition, a Grand Soul gem is required to complete the ritual (unless disabled in mod options).

Enchantment 

Homunculi Guardians can be created by constructing a physical form and animating it with magic. In addition the the resources required to create a physical form, a filled Grand Soul gem is required to power the Homunculi  (unless disabled in mod options).

Live sacrifice

Daedric princes demand greater sacrifices to support your permanent binding of their minions. To do so you must first craft (at a cooking station) or acquire inert sacrificial oil then imbue it with power with the proper incantation, and finally apply it to a weapon. Strike down an enemy with the poisoned weapon to summon your new daedric guardian (seeker/dremora). The more powerful the sacrifice, the more powerful the guardian which will be summoned.
Unless disabled, incantations require one filled grand or black soul gem to imbue the sacrificial oil.

Master level sacrifices 

Once you have successfully made two high quality (above level 35) sacrifices to a Daedric Lord, the next time you use the relevant incantation they will contact you requesting a more specific sacrifice in exchange for a master level Daedric Guardian. Your incantation spell will henceforth produce a more powerful variant of the sacrificial oil which summons an alternative, powerful Daedra when used on a specific kind of sacrifice. 

Resurrecting Dragon Priests 

Dragon priests have prepared means for their resurrection in the hope that their servants or the unwise might bring them back in the event of their defeat. You can find an ancient spell tome on dragon priest corpses that will teach you the means of doing so (see mummifying) alongside the required phylactery. This would be very unwise.

However, if you first learn a master level spell ‘bind sentient undead’ you can bind the dragon priest while they are in their phylactery and then create a powerful guardian. This requires a filled grand or black soul unless disabled in mod options. 

If you want to create dragon priest guardians on creative mode, just use the resurrect spell and select ‘bound’ from the options menu that will appear.

 
Through dialogue you can command your guardians
 
* Command Guardian Follow 
Commands targeted guardian to follow and fight for the player until dismissed. Note, when guardians are following you receive a penalty to your sneak and pickpocketing skills as you are more conspicuous. 
 
*Command Guardian Guard Location 
Commands targeted guardian to guard current location until dismissed or commanded to follow. 
 
*Command Guardian Dismiss 
Commands targeted guardian to return to their original guard location. (if you are far from these and immediately fast travel back, you may have to wait a few hours to give them a chance to catch up). 
 
*Command Guardian Hunt & Destroy 
Commands targeted guardian to hunt and destroy any enemy NPCs in a wide radius for 20 minutes or until another command is issued. This can be used to have guardians attempt to clear a section of a dungeon for you. 
 
*Command Guardian Equip 
Opens the targeted guardian's inventory allowing you to have them carry/equip items. Only available for corpse, skeletal and dremora guardians. 

Note: Corpse & Dremora Guardians will equip any weapons and armour given to them. Skeletons will equip anything except body (Chest/leg)  and hand armour, though this can be enabled in game options.

 
All advanced commands learnt after reading the adept level spell tome, Advanced Guardian Commands. 
 
Upon reading the Advanced Guardian Commands (adept) spell tome you will learn a lesser power, Advanced Guardian Commands. This will allow all guardians in a large radius to be commanded simultaneously. It will also allow a new dialogue option with Guardians which will trigger the power.
 
* Command All Guardians Follow 
Commands all guardians in a wide radius to follow and fight for the player until dismissed. Note, when guardians are following you receive a penalty to your sneak and pickpocketing skills as you are more conspicuous. 
 
 
*Command All Guardians Guard Location 
Commands all guardians in a wide radius to guard current location until dismissed or commanded to follow. 
 
*Command All Guardians Dismiss 
Commands all guardians in a wide radius to return to their original guard location. (if you are far from these and immediately fast travel back, you may have to wait a few hours to give them a chance to catch up). 
 
*Command All Guardians Hunt & Destroy 
Commands all guardians in a wide radius to hunt and destroy any enemy NPCs in a wide radius for 20 minutes or until another command is issued. This can be used to have guardians attempt to clear a section of a dungeon for you. 

*Command All Guardians Massacre
Commands all guardians in a wide radius to hunt and destroy any neutral or enemy NPCs in a wide radius for 20 minutes or until another command is issued. This can be used to have guardians attempt to wipe out a town.

Note: If you are planning to let your guardians wreak havoc in a town, I strongly suggest you pair with a mod which modifies the behaviour of essential NPCs so your Guardian's are not defeated by invincible opponents. My personal recommendation is Andrealphus' Bleedout Revamp 

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There are two other lesser powers learnt from this spell tome 
 
*Mark Friendly 
Use this on an NPC to mark them as a 'friend' to your guardians. This will prevent guardians from attacking this NPC when commanded to massacre NPCs. Use the command a second time to remove the mark. Note, this will may not work once combat has already begun.  
 
*Mark Hostile  
Use this on an NPC to mark them as a 'hostile' to your guardians. This will cause them to attack the NPC even if they otherwise would not (because they are an ally of the player for example). Note, this will cause the NPC to also become aggressive toward the player. Use the command a second time to remove the mark (note this may not be enough to end a conflict which has already begun). 

 
The first time you read any Guardian spell tome you will learn the following lesser power.

*Summon Guardian (Followers)
Summons all Guardians currently following you. Most appear directly in front of you. If you are outside, a following dragon guardian will appear above you.

Effective in combat and if they are lost.

 
 
You will start the game with a Dead & Daedric Options lesser power. If it does not trigger on mid-game install, reading any guardian spell tome will add it.

Mod Modes:
Balanced (Default)
As the mod is described on this page. In addition to any other ingredients, you need one filled soul gem to create any Guardian. This makes creating Guardians at early levels a challenge and makes the creation of huge (game-engine breaking) armies only theoretically possible. In short, it provides a sense of balance, progression and achievement.

Note that with this mode enabled an empty soul gem will be reclaimable from the dust pile remains of a defeated guardian.

Conquest
Not every fun, immersive playthrough is a balanced one. Perhaps you want to go full lich king and take over Skyrim with an undead army; you might aspire to be the next Potema or Mannimarco. If so, this mode is for you. It removes the soul anchor mechanism, so you no longer need filled soul gems to create guardians. This means you can turn every fallen man or mer into a zombie at the very least, or cut up just a few bodies to produce a more useful skeleton. Ingredients are now only needed to create your more powerful, elite force.

Note that if you you literally turn every corpse you encounter into a zombie, there may be implications for the size of your save file. Likewise, if you gather 1000+ Guardians in one place, you are going to be testing the limits of the game engine, even with actor limit fix etc.

Creative
Like Minecraft. No ingredient requirements for spells - just have fun. This is also useful for troubleshooting/testing the mod.

Skeletal guardians, atronachs and homunculi can be created just by point and cast. You still need to point at corpses to create corpse guardians and zombies. You can use the incantation spells without any inert sacrificial oil to create as many Deadland, Coldharbour and Apocrypha oils as you desire and are also given some cheat weapons when you select the mode which have sacrifice enchantments (and so don’t require oils).  Be careful not to break the game's NPC or AI limit!

Hardcore
Like balanced mode, a filled soul gem is required to create any Guardian, but an empty one is not reclaimable when they die. A mode for those who don't find balanced mode balanced enough.
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Quick Start
If you are roleplaying a character who would already know some of these spells, or just want to test them, select this and it will let you choose from a package of spells and resources based around whether you consider your character to be a novice, expert etc. in the field.
Note - they do not give you every resource required to cast every spell you will receive a spell tome for, but do give you enough resources to cast some straight away. Check your resources against the spell descriptions before casting or switch to creative mode if just testing.

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Dead Guardian Cleanup
By default, dead Guardians, or rather the ash pile they leave, behaves like the corpses of regular NPCs and are cleaned up (deleted) by the game on cell reset. This only happens when you don't travel to the cell in a long time, so can seem to take forever if it's you're lair where you regularly check back. You now have the option of enabling a quick clean up which occurs as soon as you leave the area (go through a load door or fast travel) . The only downside is you'll lose anything in their inventory you forgot to collect before leaving which is why it is not enabled automatically.
_________________________________________________________________________________________________________________________________________________
Skeletal Armour 
By default, skeletal guardians will refuse to equip body (chest/legs) and hand armours as when it has gaps, Skyrim insists on filling them with default human textures - not very immersive. If you are happy to carefully select which armour you give to skeletons (anything without gaps in it is good) then you can enable the ability to do so here.
_________________________________________________________________________________________________________________________________________________
Eye FX
By default, skeletal and  corpse guardians have an orange eye glow to distinguish them from enemy draugr and NPCs. You can, however, revert their eye glow back to blue if you prefer or select green or red options. 
_________________________________________________________________________________________________________________________________________________
Follower Penalties
By default, you receive a penalty to your pickpocketing and sneak skill when you have Guardians following you. This is to provide a gameplay reason for not travelling around with an army of Guardians to do quests where it seems silly, such as stealth mission and thieve guild quests. These penalties can be disabled here. You must command all following Guardians to guard/dismiss them and then re-command to follow to trigger the change. 

 
 
1) Does this change/affect the regular summon / reanimation spells? 
 
No, they have not been changed. The idea being that the mod spells are a different kind of necromancy and summoning, ones which creates semi-independent minions who do not require the presence of the caster to maintain.  

The mod can be played as an alternative to vanilla conjuration/necromancy, where you neglect the vanilla spells in favour of guardians (which is typically how I play it if using Conquest mode) or alongside the vanilla spells/minions (which is how I typically play when using Balanced mode).
 
2) Is this compatible with... 
 
Short answer - Almost anything.

Long answer - My mod edits a few vanilla vendor/death item lists to makes these spells and resources purchasable from spell vendors and lootable from enemies. This may cause an issue if you are using another mod which modifies the same level lists and are not using anything which patches level lists. (Wrye Bash can be download and used to do this https://www.nexusmods.com/skyrimspecialedition/mods/6837). If you don't patch these lists, then one mod will override the other's changes. If another mod did override Undead Guardian's changes, you could still find all the spells and resources from a non-vanilla vendor at the Necromancer's Market however. 

Another issue would be if a mod removes or radically changes one of the ingredients for a guardian so it cannot be detected. GIST seems to cause this issue for grand soul gems.

Your mod manager may prompt you about overwrites if you are using one of Mihail's mods I have used assets from. It should not make any difference which mod you let win the conflict, unless Mihail has updated his meshes/textures and I've yet to update the mod. In which case let Mihail win to use the new textures/meshes or mine to use the old.

3) Aside from the new daedric guardians, has anything changed from the original Undead Guardians mod?

Yes, bug fixes and quality of life tweaks which would take a really long time to list but definitely make it worth it to use the newer mod over the old one even if you only want to raise the undead. Skeletal guardians have been greatly improved.


4) Does this work with NPCs React to Necromancy or Skyrim Reputation?

• NPCs React to Necromancy works out-of-the-box, no patch required. Dialogue and responses are conditioned on the presence of the active magic effect that goes along with regular undead summons/reanimations. I have spoofed the magic effect when guardians are following, which is then removed when they are asked to guard, are dismissed,  or die. Likewise, reanimating, summoning or interacting with guardians will provoke the same response for 2 minutes, even if they are not following you.
Limitations - It will occasionally produce false negatives (NPCs won't notice your guardians) but this is to eliminate the chance of false positives (NPCs complaining about ones that aren't there) . You are unlikely to notice this in regular gameplay unless compulsively checking for the magic effect. This will self correct during combat, or can be forced by asking a guardian to follow again.

• Skyrim Reputation requires a patch available in the option files section. This allows the mod to recognise appropriate Guardian spells as Necromancy, adding to the  'Seen Necromancy Count' when performed in front of townsfolk. Using Skyrim Reputation alongside D&D Guardians will mean you have long-term reputational consequences for openly practising necromancy (which can be avoided by doing so covertly). 

5) Is this really balanced? Just how strong are these Guardians that I can potentially create an army of? 
 
Consider the balance factor of D&D Guardians from the perspective of alchemy rather than conjuration. You can theoretically invest a lot of time into gathering all the resources needed to make an army, storing them way somewhere safe until needed, just as you can hoard potions. You can then use that army to overcome a strong enemy or dungeon you would not be able to defeat without them, but you will exhaust your supply in the process (some will die) and will need to reinvest time into gathering the resources to rebuild. There are several mod modes to tweak the balance by modifying resource requirements (see mod options)
 

6) I've been travelling with my favourite Guardians, I call them Jack and Jill, and then after I fast travelled around a bit I noticed they were gone. Did they die? Have they gone home? Where are they? 
 
First step, use the Summon Guardian Followers lesser power and see if they show up. 

You should receive a notification (top-left) when a guardian dies. One possibility is that you missed it and they died in battle. Try retracing your steps. 
 
There is a vanilla Skyrim bug with followers (including dead thralls) where they get lost when you fast travel about too much. However, this has been fixed (or atleast made rare) for Guardians in recent updates. 
 
If you really cannot find them and the summon command isn’t working try the following:
- save your game
- use the console command player.kill (which will kill your players, but trust me)
- use the summon command again once the game reloads.

7) Are guardians affected by perks or spells from [insert perk overhaul/spell pack here]

As far as the game is concerned, Guardians are:
- undead/daedra
- allies
- teammates (followers) when following (some technically remain 'teammates' when guarding so they don't revert to their default outfits)

Perks or spells that only use one or more of these as conditions will affect them.

However, conjuration perks and spells aimed at summons/reanimations may be set up with the condition ‘is command actor’  - which is used for regular summons/reanimations. Unfortunately, not being a commanded actor is essential to guardians working as they do.

The RP excuse for this is that Guardian spells are about creating minions which are semi-independent of you. Just as they don’t require your presence to be, they also don’t benefit from such passive powers. 

Perks that depend on the presence of the active magic effect on the player which goes with regular summons/reanimations (e.g. Ordinator’s Edge of Oblivion) will work when a guardian is following as I have spoofed this effect.

8) Will using these spells / guardians level conjuration?

Yes, you receive a healthy dose of conjuration EXP when creating a guardian and a small amount whenever a Guardian attacks something. 

Note the amount you receive for creating one is dependent on mod mode - most for Balanced/Hardcore mode, some for Conquest, none for Creative. The amount you receive for a guardian attacking is dependent on the level of what they are attacking.

8) The textures on head and body parts of my Corpse Guardians don't match up when they are wearing armour with gaps. Help?!

You are using a texture replacer for draugr, perhaps as part of package of textures, which makes them different enough from vanilla skins that  the draugr skin put into the gaps of armour contrasts with it to a noticeable degree. If you don’t like vanilla textures, try DRAUGR at Skyrim Special Edition Nexus - Mods and Community (nexusmods.com) which is close enough to vanilla that you won’t notice, but still looks better.

9) Is this mod of any use for spell-sword / low magicka characters?

Most high level guardian spells are pretty magicka intensive, but you can be a Daedric cultist, sacrificing living NPCs in exchange for  Daedric Guardians with very little magicka. The logic being that you are relying of the power of the sacrifice and good will of a daedra lord to summon these guardians.

You can always lower the magicka cost of other spells with a mod like Proteus if you really want too.
 
10) Is this available on console? 
 
It is available on Xbox. 

11) Is this available on LE? 
 
No, but I give permission to port it to anyone willing.

12) Does this work on both regular SE and AE Skyrim?
 
Yes, it makes no difference which you are using.

13) Is this mod ‘script heavy’?

If you look in the scripts folder you’ll find a good number of scripts, as you would find in  any advanced follower mod, but they are all of the relatively short, fire-once variety. I use DnD Guardians heavily and have had saves with large numbers of guardians guarding locations and following - DnD guardians has never been responsible for any script lag I’ve encountered when I’ve had to investigate via Falrim tools

 

 

If the summon command doesn’t summon all guardians it should, save game and use the console command player.kill , killing your character and reloading the game. For reasons I won’t pretend to understand this fixes the issue. If the problem persists, then please make a bug report.
 

 
 
1) A note on casting 
Guardians will look in the direction they were originally cast when guarding their spawn location (they are cast with their backs to you). So if you want a guardian to guard a chest, stand in front of the chest looking away from it and cast near your feet. It will now be standing in front of the chest looking out. The same applies for corpse guardians. Although the spell must target the corpse and they may move slightly to the left or right of its original location, they  will spawn facing away from you. 
 
2) A note on harvesting & reanimating 
When harvesting a corpse using the spell or tool, the body is destroyed, but the inventory can be looted after the fact by activating the bloody rags which remain. When creating a zombie guardians, any non quest items disappear (this stops over encumbering you and your save file). When creating corpse guardians, the inventory of the dead NPC is automatically transferred to you, and their inventory will open for you to reequip the items if you so desire.

3) Massacre command beats Hunt & Destroy 
 
You’d think creating a command to hunt and destroy enemy NPCs and creating a command to massacre enemy/neutral NPCs would be similar but due to quirks of Skyrim I had to go about these in very different ways. The end result is that massacre command leads to much more effective AI hunting behaviour than Hunt & Destroy. As such, if you’re in a dungeon and there are no neutral NPCs you’re worried about your guardians attacking, you’re best to use the massacre command.

4) Friendly Fire Protection

There are a few layers of friendly fire protection built into the mod.

Guardians are all scripted to ignore friendly fire from the player. Spells from guardians do not harm other guardians, the player, or anyone marked as teammate (all vanilla followers and most custom). If fights do break out, melee, ranged and spell attacks from guardians trigger a script that ends combat when they hit a teammate, fellow guardian or essential NPCs. Issuing  any all Guardian Command should also trigger guardians to stop fighting each other. 

It's still Skyrim though, and Skyrim can be weird.  Summons of teammates can be a problem; the custom follower Remi's pet dwarvern spider, Scrap, likes to...uh... scrap with guardians  (and everyone else!) once she learns her lighting spell. Guardians may also take sides in fights between other mod added allies who have been set up in an unusual way. Still, this is one of the safest mods out there to have a large spell wielding party of followers.

5) Active Magic Effects when Guardians follow
I have spoofed an effect vanilla summons/reanimations cause so the base game and mods like NPC's React to Necromancy can detect when you have guardians following. There is also a pickpocketing and sneak reduction effect (-50 points) to give an immersive-ish gameplay reason not to take whole armies with you when it seems silly, like while doing thieves guild quests. 

   
Mods which let you become a lich because of course they do  
  
Undeath Remastered + Classical Lichdom + Dragon Priest Fix - Behaviour Overhaul  + Undeath Classical Lichdom - The Ascension (Lite)
 
-or-  
 
The Path of Transcendence – Lichdom 

NPCs React to Necromancy
Highly recommended - Increases immersion by having NPCs react very negatively to you sauntering into town with an army of undead. Giving you a reason to leave them back at your lair, outside the gates, or use more tolerated daedric summons. For more info on how this mod interacts with D&D Guardians see FAQ 4.  

Skyrim Reputation (Patch required - see optional files)
Like above, leads to consequences for openly practising necromancy, but of the long-term reputational variety. I'd suggest using both NPCs React to Necromancy and Skyrim Reputation (+patch) for maximum immersion (you'll be hated/feared, or have a reason conceal evidence of your necromancy)
 
Disable Follower Collision (SE) / I'm Walkin’ Here (AE)
If you're planning on adventuring with 8 or so Guardians, or perhaps 5 Guardians, a follower and two regular Dead Thralls,  then this mod is a must. Allows you to pass through anything that is following you, so you won't get stuck entering dungeons and homes with a large party . If you are using AE, then substitute this with I'm Walkin' Here, which achieves the same.
 
CC Zombies for Undead Guardians
If you have the CC zombie content and prefer their zombie model to Mihail’s that I’ve used, this patch will swap in the CC versions. 

Mods which give you something you need guardians to defend a location against

- Organic factions + Organic Factions Extension
Set up a base somewhere that one of the undead unfriendly factions visit, such as ravenscorn spire, or try and take and hold one of their bases

- Conquest of Skyrim
Guardians can provide extra defense or help with assaults - reports are this mod plays very nicely with D&D Guardians

-Tundra Defense
make a base and expect semi-regular assaults

Player Homes 

- BoneHawk Prison 
A necromancer themes player home designed with Undead Guardians in mind.
https://www.nexusmods.com/skyrimspecialedition/mods/72186

 - The Black Sepulchre
A suitable necromancer/vampire evil lair (player home) you could fill with guardians. (Credit to skunkjohnson for the recommendation) 

- anything by SlimeSire https://www.nexusmods.com/users/84859838?tab=user+files

- Hearthfire Extended
It’s not advertised as such, but you can use the mod to move into a dungeon. 

Vanilla+ perk & spell overhauls 
Because these don’t themselves try to significantly expand/overhaul necromancy the result of them + this mod is cleaner 
 
Adamant, Mysticism etc.   
 
(SimonMagus616's profile at Nexus mods and community)

Scrambled Bugs
There are many reasons for having this mod, but with respect to DnD Guardians, enabling the Poison Resistance fix will prevent NPCs occasionally resisting Sacrificial Oil

Jaxonz Renamer 
So that after you have ripped out Nazeem’s soul and put it in a Skeletal Guardian you can rename the Guardian Nazeem. (Credit to CorvusTheFallen for the recommendation) 

Morbus Immortui - Revenancy 
An alternative to a lich playthrough but of a similar vein, adds a new undead form/transformation (Credit to 12derp for the recommendation) 
 
Command Undead and Lasting Undead 
Why make your own undead when there are plenty of undying minions just lying around the place? (Credit to 12derp for the recommendation) 
 
Store bodies in scrolls 
Useful mod for moving corpses around ready for creating corpse guardians at a later time or different location to that they were killed (Credit to 12derp for the recommendation) 

Dead NPC Body Cleaner Remover
There is a difficult-to-fix issue where if you harvest a corpse, then leave the area, then come back (reload cell) during the time period after the game has forgotten about the effects that 'harvesting' applies to the corpse, but before it has cleared up dead NPCs, you will see a miraculously regenerated, intact copse. It is not a gameplay issue (you cannot reharvest), but can be immersion breaking. This mod will eliminate the issue by speeding up how quickly corpses are removed from the game. (Credit to Custard 91 for discovering) 
 
If you have recommendations for expanding this list please share   
 
 

   
 
The following mods have soft incompatibilities. In other words, they do similar things to this mod leaving some immersion breaking overlap.  
 
Corpse Preparation – Most similar to this mod. Choose one or the other. It’s an older mod with more features, but with more limits on what can ultimately be achieved. While I have tried not to stray too far from lore and looked to in game texts for inspiration, this mod goes further by sticking religiously to necromancy as described in the in-game text which is its namesake, Corpse Preparation.  My mod is lighter by comparison and I prefer my design decisions from a gameplay perspective, but I am obviously bias so feel free to check out both and decide which suits you.    
 
The Dark Arts - This mod offers a full overhaul of the necromancy system, far beyond the scope of mine, but does not cover the core feature of this mod. It works alongside D&D Guardians, and for some may feel like a natural partner, but you might find having two separate ‘harvest’ systems immersion breaking. 
 
Ordinator 
If you go down the bone collector branch of Ordinator’s conjuration tree, you will have two sets of ‘bone’ resources for the undead guardian and Ordinator skeletons. You can avoid that part of the perk tree or not use skeletal guardians to get round this. 
 
Interesting NPCs 
Anum-La (npc added by mod) is going to find herself in the middle of the Necromancer’s Market. She doesn’t seem to mind. 
 
Actually incompatible  
It has been reported that GIST prevents DnD Guardians from recognizing filled grand soul gems in the players inventory (needed for atronach and homunculi guardians in balanced mode). No other soul gem management mod seems to have issues.

 

 
 
Abbalovesyou kindly agreed to let me use assets from Playable Draugr & Extra Playable Skeletons, so as to allow some Undead Guardians to equip armour and weapons. This would have taken a huge amount of time without these assets and so I am very grateful. 
Playable Draugr SSE at Skyrim Special Edition Nexus - Mods and Community (nexusmods.com) 
 
I have used Mihail's Zombie, Scamp, Havocrel and Daedroth meshes and textures. He has a wonderful approach to asset sharing and has created a huge number of monster and enemy mods - check them out here:https://www.nexusmods.com/skyrimspecialedition/users/37834630?tab=user+files  If you like my mod enough to endorse - please spare a moment to endorse his as well.  Thanks Mihail (again) and QuentustheBosmer who repackaged his textures/meshes to work as armour for his mod Playable Ancient Skeleton Armor https://www.nexusmods.com/skyrimspecialedition/mods/64668 - used for reinforced and mage skeletons.

I have used assets from fadingsignal's Giant Footstep Camera Shake removal to remove the footstep shake from Lurkers. Giant Footstep Camera Shake Remover at Skyrim Special Edition Nexus - Mods and Community (nexusmods.com)

I have used assets from tx12001's ENERGY EYES - Dragon Priest Eye Glow Replacer for the dragon priest red eye glow effect. ENERGY EYES - Dragon Priest Eye Glow Replacer at Skyrim Special Edition Nexus - Mods and Community (nexusmods.com)

Huge thanks to CorvustheFallen for helping me to clean the original mod, Undead Guardians, of unintentional dirty edits before I learnt to do so.